We propose to observe three blazars, namely, Mrk 421, 1ES 1959+650, and 3C 454.3 continuously for 100 ks each with SXT, and repeat the same observations later in the cycle. Using additional archival light curves, we shall precisely determine the X-ray power spectral density (PSD) at hours to years timescales. While detailed X-ray PSD of several Seyfert galaxies --- where the X-rays are from the accretion disk-corona region --- have been obtained before, that of blazars is much rarer. We shall search for any characteristic timescale (e.g., a break) in the PSD and hence test if such patterns translate from the accretion disk to jet. This work will help put additional constraints on the disk-jet connection in AGN. Correlation of multi-band variability from other instruments will provide clues about the mechanism of short-timescale variability in jets possibly driven by radiation loss and turbulence.

We request four 25ks AstroSat observations of NGC1365 with UVIT as the primary instrument. NGC1365 is a Seyfert 1.8 galaxy well known for extraordinary variations of X-ray absorption on short and long timescales. NGC1365 frequently exhibits X-ray eclipses, possibly by the broad-line region clouds, on hours timescale. It also shows Compton-thin to Compton-thick transitions on months-to-years timescale. These dramatic X-ray absorption variations have never been studied in conjunction with optical and ultraviolet observations, to search for associated flux and colour variations in these bands. The main aim of this proposal is to study in detail the X-ray absorption variability of this source, and to search for accompanying variations in the optical spectrum and optical/UV colours with coordinated AstroSat/SALT observations. The proposed observations will also probe if there is a connection between the hard X-ray continuum and the low energy X-ray absorption, and thus to separate absorption and intrinsic X--ray variability.

The globular cluster Terzan 5 contains numerous transient low-mass X-ray binaries. At least three of these have undergone X-ray outbursts over the past 15 years, showing a variety of intriguing behaviours. We propose a 40 ks AstroSAT observation of the next bright outburst from Terzan 5, to measure its X-ray energy spectrum, characterize its power spectrum, search for pulsations, and study any X-ray bursts that occur.

We request to observe one bright Seyfert 2 AGN, NGC 4388 for 50 ks with ASTROSAT/SXT, LAXPC and UVIT. The existing RXTE observation of NGC 4388 revealed variability in the absorption column density by a factor of 10 on timescales of 4 hours. As the soft X-ray (E<3 keV) emission is very sensitive to absorption by the circumnuclear material, the study of the hard X-ray emission above 3 keV is the only way to investigate the central engine of the Seyfert 2 galaxy which is obscured by the surrounding torus. The primary goal of the proposed observation is to investigate the nature of the energy and rms spectra below and above 10 keV in order to distinguish between the variability caused by the direct nuclear emission and absorption due to the BLR clouds and/or molecular torus. This study will allow us to test the universality of the AGN unification scheme.

Her X-1 is to be intensely observed by UVIT, SXT, LAXPC, and CZTI instruments for one full binary during main high state. The neutron star illuminates the companion star, accretion disk, accretion stream and disk corona. This causes detectable X-rays and UV from these structures which are orbital phase dependent. Modelling of the orbital-phase dependent light curves in multiple energy band will be used to map these structures in the binary system. Time delays between the pulsations in the different energy bands will enable extraction of line-of-sight travel time delays and distances. The expected scientific results are: i) to obtain the geometry of the X-ray heating of HZ Her, the accretion disk, the accretion stream and the corona; and ii) to precisely determine the inclination of the binary. The improved system inclination will allow precise binary parameters and result in a well-determined neutron star mass.

M31 is the nearest giant spiral galaxy for which we can study the supernova remnants, X-ray sources, and stellar populations. At a distance of 780 kpc, M31 is far enough away that the brightest stars are safe to observe with UVIT, yet close enough to obtain a good census of the supernova remnants, X-ray sources, and hot stellar populations. The high spatial resolution of UVIT will yield outstanding data on the stellar populations of M31. The spatial resolution of SXT is sufficient to resolve the X-ray source populations which includes measuring the supernova remnant population. The resulting multi-wavelength images of M31 will form a legacy dataset to be used for study of the stellar populations of M31, it star formation history and the structure of the galaxy.

M31 is the nearest giant spiral galaxy for which we can study the supernova remnants, X-ray sources, and stellar populations. At a distance of 780 kpc, M31 is far enough away that the brightest stars are safe to observe with UVIT, yet close enough to obtain a good census of the supernova remnants, X-ray sources, and hot stellar populations. The high spatial resolution of UVIT will yield outstanding data on the stellar populations of M31. The spatial resolution of SXT is sufficient to resolve the X-ray source populations which includes measuring the supernova remnant population. The resulting multi-wavelength images of M31 will form a legacy dataset to be used for study of the stellar populations of M31, it star formation history and the structure of the galaxy.

Study of spectral and timing properties of different source states, and transitions among them, are used to probe the accretion processes and various X-ray emitting/absorbing components of neutron star low-mass X-ray binaries. Such properties and transitions are poorly observed for low accretion rates. 4U 1724-30, being a rare low-luminosity, persistent source, which shows broadband X-ray spectrum covering the entire AstroSat range, varieties of timing features, and state transitions, is one of the best sources to study accretion processes in the low accretion rate regime. Our proposed three AstroSat observations of 4U 1724-30, each of 10 ks, will find this fluctuating source in different states, and will be useful to study their spectral and timing properties and their transitions. This will advance the knowledge of the low accretion rate regime, and will characterize this less studied source. This proposal relies on the unique broadband and timing capabilities of AstroSat.

Globular clusters having a large number of stars can be used to substantiate stellar evolution models. We propose to observe an extremely metal poor globular cluster in our Galaxy that has been observed in the GALEX fields. We propose to observe this globular cluster through UVIT filters to characterise the stellar population, particularly the UV bright stars such as horizontal branch stars.

Despite intensive studies of the ultraluminous X-ray sources (ULXs) both in X-rays and in optical, there is still no strong and obvious evidence to distinguish among two competitive models: whether they contain stellar-mass or intermediate-mass black holes (IMBHs). What we know exactly is that the ULXs are close binary systems with massive donors. We propose to test the components of the ULX binaries. Recent data show that both UV and optical emissions may be reprocessed in strong heating by X-rays, where UV-optical spectral energy distribution hints at two-component spectra. We propose simultaneous observations of the X-ray variable ULX Holmberg II X-1 with ASTROSAT to test the UV and optical responses to the X-ray variability. Our mail goal is to study correlations between the X-ray-UV-optical data, and to elucidate the model as either a donor and supercritical accretion disk, or a donor and standard irradiative accretion disk with IMBH.

We propose UV and X-ray observations with instruments UVIT, SXT, LAXPC and CZTI on board AstroSat, of three radio-loud narrow-line Seyfert 1 galaxies (RL-NLS1s) namely B3 1702+457, MRK 766 and 1H 0323+342. These RL-NLS1s exhibit intra-night optical variability and 1H 0323+342 is also detected in gamma-ray with Fermi-LAT. Our aim is to understand the emission mechanisms in RL-NLS1s by studying components characterizing broad-band spectra and multi-band variability. The simultaneous UV to hard X-ray data from AstroSat combined with co-ordinated optical, IR data (from Mt. Abu) and radio data (from GMRT) will allow us to make first attempt to study these RL-NLS1s with simultaneous multiwavelength observations across radio to hard X-rays. In order to obtain spectra with good signal-to-noise ratio we request 80 ks observation for each source, and thus a total observing time of 240 ks (~ 67 hours).

Understanding the precise star-formation history of galaxies and its dependence on galaxy mass, morphology and environment is one of the most important outstanding problems in galaxy evolution. UV data, which are the most precise probe of (relatively unobscured) recent star-formation are crucial to resolving degeneracies in the modeling. For nearby galaxies of large angular size, such modeling can be carried out for individual star-forming regions. For this purpose, the unprecended angular resolution of UVIT is critically required. In this pilot study, we request UVIT observations of 5 nearby S0 galaxies, which show some evidence of recent star-formation. We will combine the UVIT UV data with archival observations in optical, near-IR and mid-IR and stellar population synthesis models to model the resolved star-formation histories of these galaxies.

Understanding the precise star-formation history of galaxies and its dependence on galaxy mass, morphology and environment is one of the most important outstanding problems in galaxy evolution. UV data, which are the most precise probe of (relatively unobscured) recent star-formation are crucial to resolving degeneracies in the modeling. For nearby galaxies of large angular size, such modeling can be carried out for individual star-forming regions. For this purpose, the unprecended angular resolution of UVIT is critically required. In this pilot study, we request UVIT observations of 5 nearby S0 galaxies, which show some evidence of recent star-formation. We will combine the UVIT UV data with archival observations in optical, near-IR and mid-IR and stellar population synthesis models to model the resolved star-formation histories of these galaxies.

Requested observation: Propose to observe Cyg X-2 using LAXPC for an effective exposure time of 20 ks. Context: Cyg X-2 is a prototype of Z-type sources showing a horizontal, normal and flaring branches in the X-ray colour-colour diagram (CCD) and QPOs in the respective branches. The spectrum is modeled with multi-temperature black body along with a Compton tail in the high intensity state. Objectives and Expected scientific results : We would like to study the correlated spectral and temporal variation of the source as source traverses a Z track in CCD. We propose to study the cross-correlation functions of energy dependent light curves (i.e. 3-5 keV vs 10-20 keV, 20-50 keV). We would like to explore the auto-correlation functions in various energy bands inorder to constrain the reprocessing models. The origin of 6 Hz QPO would be explored using the data.

The recent discovery of swings between an accretion powered (X-ray) and a rotation powered (radio) pulsar state from the transient IGR J18245-2452 in the globular cluster M28 proved the evolutionary link shared by these two classes of sources, and showed that transitions between these two regimes can take place over timescales as short as a few weeks, depending on the variations of the mass accretion rate. IGR J18245-2452 also showed dramatic variations of the X-ray flux on a shorter timescale, possibly due to propeller centrifugal inhibition of accretion. These properties make it the ideal case to study the disk-magnetosphere interaction around a fast pulsar. We propose an anticipated ToO 60 ks observation of IGR J18245-2452 during the next outburst of the source, to measure the long term spin and orbital evolution of the pulsar, and follow its correlated magnitude-spectral variability over a broad 0.3-80 keV band.

We propose a 15~ks UVIT observation of the Seyfert~1.5 galaxy Mrk~0926, along with SXT and LAXPC for a detailed broadband SED modelling of the source. We have multi-wavelength data from XMM-Newton,SDSS,WISE and UKIDSS/2MASS for a sample of type~1 AGN including Mrk~0926, one among the hardest X-ray sources in the sample. Though EPIC-pn data are available, the energy coverage is limited to 0.2-10~keV. The proposed observation will help us to extend our study by including X-ray data from 0.3-80~keV.The simultaneous multi-wavelength capability of ASTROSAT can better constrain the SED fit with UVIT observations in the optical/UV band, in addition to SDSS data. The modelling will be done using the self-consistent energy-conserving model optxagnf which can accurately determine the bolometric luminosity and well constrain parameters like Eddington-ratio and hard X-ray photon index.These observations will also help to study the short time-scale spectral variability of the source in the UV and X-ray bands.

The nature of the ultra-dense matter in neutron stars remains enigmatic and there is still a wide variety of possible internal compositions. Obtaining accurate radii and masses for neutron stars will allow to distinguish between these equations of state. We have suggested a powerful way to constrain both neutron star radii and masses by combining a measure of the inner disk radius from broad iron emission lines and the frequency of kHz quasi-periodic brightness oscillations (QPOs). However, this method only works if both phenomena originate from the same part of the disk. Here, we propose 30 ks observations of each of the neutron star low-mass X-ray binaries GX 349+2 and GX 340+0 to simultaneously obtain an accurate measure of the inner disk radius from broadband spectroscopy and the kHz QPO frequency from timing.

Defying traditional wisdom, several star-forming galaxies have been discovered in galaxy clusters in the last decade. These galaxies are a rare class of transition objects ``caught in the act", and therefore provide essential clues for understanding the evolution of galaxies from being actively star-forming spirals and irregulars in the sparse environments, to passively-evolving spheroids in the core of groups and clusters. We propose to observe 4 such star-forming galaxies falling into clusters identified by their distorted morphology in far ultraviolet images. We intend to image these galaxies with UVIT. Together with the ancillary optical and infrared data, and complimentary 21 cm imaging proposed for the GMRT, we will use the Astrosat data to explore the extent of the tidal tails and the impact of gas loss on the morphology of the infalling galaxies. We will also study star formation efficiency in these galaxies undergoing tidal stress.

We propose to do a pilot study of the UV emission from the low luminosity stellar disks of five spiral galaxies that have extended ultraviolet (XUV) disks. Our targets have all been detected by GALEX. They are all nearby spirals that we have selected based on UV luminosity. XUV galaxies show filamentary or diffuse star formation well beyond their optical disks, in regions where the disk surface density lies below the threshold for star formation. GALEX found that 30% of spiral galaxies have XUV disks. The star formation is thought to be triggered by gas accretion from nearby clouds, galaxies or the intergalactic medium. In this study we will investigate the nature of XUV disk star formation, estimate its rate and morphology. The high sensitivity of UVIT will help isolate the star forming knots, image the UV disks and search for signatures of gas accretion.

We propose to do a pilot study of the UV emission from the low luminosity stellar disks of five spiral galaxies that have extended ultraviolet (XUV) disks. Our targets have all been detected by GALEX. They are all nearby spirals that we have selected based on UV luminosity. XUV galaxies show filamentary or diffuse star formation well beyond their optical disks, in regions where the disk surface density lies below the threshold for star formation. GALEX found that 30% of spiral galaxies have XUV disks. The star formation is thought to be triggered by gas accretion from nearby clouds, galaxies or the intergalactic medium. In this study we will investigate the nature of XUV disk star formation, estimate its rate and morphology. The high sensitivity of UVIT will help isolate the star forming knots, image the UV disks and search for signatures of gas accretion.

We propose to do a pilot study of the UV emission from the low luminosity stellar disks of five spiral galaxies that have extended ultraviolet (XUV) disks. Our targets have all been detected by GALEX. They are all nearby spirals that we have selected based on UV luminosity. XUV galaxies show filamentary or diffuse star formation well beyond their optical disks, in regions where the disk surface density lies below the threshold for star formation. GALEX found that 30% of spiral galaxies have XUV disks. The star formation is thought to be triggered by gas accretion from nearby clouds, galaxies or the intergalactic medium. In this study we will investigate the nature of XUV disk star formation, estimate its rate and morphology. The high sensitivity of UVIT will help isolate the star forming knots, image the UV disks and search for signatures of gas accretion.

We propose to study the persistent microquasar GRS 1758-258 for a total exposure of 30 ksec using SXT, LAXPC, CZTI and UVIT on-board AstroSat. SXT will be considered as the primary instrument. The source is a persistent confirmed black hole source, with bipolar radio jets observed from the core. The previous studies suggest that the source has occupied different types of spectral states. We propose to perform a correlated study of the UV and X-ray characteristics. The correlation between spectral state transition and radio emission/jet will also be explored. We will investigate the nature of Quasi-periodic oscillations, energy dependency of fractional variability, time resolved spectroscopy and time lag variation. Finally, we will model the broadband spectra so as to estimate the accretion flow parameters and to put a constrain on the mass of the black hole source.

Requested observation: Propose to observe IGR J16167-4957 using SXT for an effective exposure time of 15 ks and LAXPC for 15 ks. Context: IGR J16167-4957 is considered to be a hard IP source but there has been no detection of spin or orbital periods yet. A QPO was observed at 585 s but vaguely proved. Spectrum is hard along with an iron line. Objectives and Expected scientific results : Search for spin and orbital periods of this source and constrain any QPOs in this system. Study the temporal and spectral evolution and compare them with other IP sources, thus strengthening its candidature as an IP. Study the cross-correlation function and auto-correlation function to constrain the accretion geometry.

We propose a 40 ksec observation of 4U 2206+54 with Astrosat for better estimation of spin period and establish the presence/absence of cyclotron line in the pulsar. Though the nature of the compact object was unknown for long, recent detection of 5560 s pulsations confirmed the X-ray source as a neutron star. Investigation of spin period evolution of the pulsar imply the surface magnetic field to be ~10^14 G, comparable to that of magnetars. However, recent observational results are in disagreement with the magnetar nature of the X-ray source. Reports of detection of a cyclotron line at ~30 keV in the spectrum of 4U 2206+54 remains debatable till date. Using the proposed Astrosat observation, timing and spectral studies of 4U 2206+54 will help in establishing the presence of cyclotron line in the pulsar and estimate the magnetic field and spin period of the pulsar with better accuracy.

Investigation of stellar coronae and chromospheric activity is one of the frontier areas of research in X-rays and UV. ASTROSAT’s capability to observe such sources simultaneously multi-wavelengths is a powerful tool to understand these activities and their inter-relationship. We propose to observe a low mass rapidly rotating highly active stars simultaneously with the UVIT, SXT and LAXPC instruments onboard ASTROSAT. We intend to study highly time-resolved correlations of coronal, chromospheric and photospheric activity phenomena. The requirement of strictly simultaneous observations results from the short-lived nature of the activity signatures under study. Hence, intensity variations will be studied over a time-scales as short as a few seconds. The proposed observations will yield insight into the nature of the associated magnetic dynamos.

We request observations of the "extreme" TeV blazars, RGB J0710+591, using the multiwavelength instruments on board the ASTROSAT. We propose for 1 pointing of 40 ks. The proposed observation will provide unprecedented spectral resolution of the synchrotron peak and beyond of the so called class of EHBLs, which peak in the hard X-rays. Since the origin of the optical emission of these object is under debate, simultaneous UV-Xray bservations using ASTROSAT can resolve this uncertainty. Study of the hard X-ray spectrum, along with TeV observations, can give us hitherto unknown clues on the extragalactic background light and also the physical processes responsible for the outbursts in blazars.

We propose to study the source 1E 1740.7-2942 for a total exposure of 10 ksec using SXT, LAXPC, CZTI and UVIT. SXT will be considered as the primary instrument. The source 1E 1740.7-2942 is a persistent microquasar with double-sided radio jets, and is observed to stay in hard state most of the time. An occasional spectral state transition exists implying presence of soft disk emission as well. We would like to study the broad-band spectral and temporal characteristics of the source. This will focus on correlated X-ray and radio behaviour, variation of radio emission during spectral state transition change in accretion dynamics and correlated UV and X-ray characteristics as well. Excellent timing capabilities of LAXPC will be used to search for low frequency QPOs and study energy dependency of rms variability and time lag. We plan to perform a broad-band X-ray spectral modeling to estimate the mass of the source.

CZT-Imager onboard AstroSat has significant polarization measurement capability at energies beyond 100 keV. Crab is a potential candiate for X-ray polarimetry observations with CZTI. Pulse phase resolved polarization measurements of Crab will be helpful in constraining the pulsar emission mechanism models and geometry. We have obtained statistically significant polarization signature for Crab from the available CZTI data (~481ks) when averaged over all phases. Estimated degree of polarization is ~35% with polarization angle ~140 degree which are consistent with previous measurements. We also have obtained estimates of polarization of the off-pulse emission which is found to be higher than the average. Significant polarization measurements in all phase bins require further observations of the target. Hence we propose 500ks observation of Crab and 60ks of blank-sky observation for background estimation. We estimate that this observation along with available data would allow to have at least 3-sigma polarization measurements in various phase bins.

CZT-Imager onboard AstroSat has significant polarization measurement capability at energies beyond 100 keV. Crab is a potential candiate for X-ray polarimetry observations with CZTI. Pulse phase resolved polarization measurements of Crab will be helpful in constraining the pulsar emission mechanism models and geometry. We have obtained statistically significant polarization signature for Crab from the available CZTI data (~481ks) when averaged over all phases. Estimated degree of polarization is ~35% with polarization angle ~140 degree which are consistent with previous measurements. We also have obtained estimates of polarization of the off-pulse emission which is found to be higher than the average. Significant polarization measurements in all phase bins require further observations of the target. Hence we propose 500ks observation of Crab and 60ks of blank-sky observation for background estimation. We estimate that this observation along with available data would allow to have at least 3-sigma polarization measurements in various phase bins.

We are proposing 23 ks effective exposure of the X-ray burster 4U 1820-30 using SXT, LAXPC and CZTI instruments on-board AstroSat satellite. The source 4U 1820-30 is a low-mass X-ray binary (LMXB). 4U 1820-30 is famous for kilo-hertz QPO, thermonuclear bursts and burst oscillations. These features of 4U 1820-30 have been mostly observed by RXTE/PCA and not confirmed by any other instrument. RXTE/PCA was also limited to ~ 25 keV. AstroSat LAXPC will provide an unique opportunity to observe these features as LAXPC have wide energy coverage from 3.0 – 80.0 keV with large area and high time resolution and thus enable us to do energy dependent timing analysis.

We propose four observations (each three weeks apart) of the rapidly variable Seyfert 1.5 galaxy NGC 3227, each of 40 ks. NGC 3227 has an average accretion rate (0.5% Eddington) similar to that at which Cygnus X-1 changes from harder-when-brighter to softer-when-brighter behaviour. Cyg X-1 has a total spectrum consisting of two powerlaws. The harder powerlaw is driven by synchrotron seed photons from the X-ray emitting corona and the soft by blackbody photons from the accretion disc. However rms spectra show only one, soft, powerlaw. Here, with total and rms spectra from each of the 4 observations at different flux levels, we will test whether NGC 3227 shows the same behaviour. Previous Suzaku observations hinted at similar two powerlaw total spectra but provided no rms spectra. Astrosat has far superior spectral coverage, particularly above 10 keV, allowing far better discrimination between powerlaws and the reflection components which confused earlier work.

We propose an ASTROSAT observation of the HMXB Be binary 1A 0535+262 in order to probe the quiescence state of this source. This source has shown X-ray luminescence and pulsations during low mass transfer periods in multiple observations despite the fact that at very low accretion rates, spherical accretion is expected to be inhibited due to the propeller effect of the spinning neutron star. Given the presence of pulsations during some of the quiescent phase observations, which in turn indicate accretion onto the polar caps, we expect the presence of cyclotron resonant scattering features (CRSF) too (at ~ 45 keV ) during quiescence, which though have not been seen yet. Probing this with ASTROSAT’s higher sensitivity in the CRSF energies, would enable constraining the low mass accretion and magnetic field configurations during quiescence. This will also allow measurement of the hard X-ray pulsations in quiescence for the first time.

Recent discovery of a 1.2 second modulation in M 31 (Andromeda galaxy) has indicated the presence of a pulsar 3XMM J004301.4+413017 (3X J0043), which hosts a neutron star. This is the first accreting binary system in M 31, for which the spin-period has been identified. We request a 50 ks observation using LAXPC instrument on ASTROSAT. The main objective of this proposal is to detect pulsations and carry out an energy resolved pulse profile analysis. There are ~200 accreting pulsars in our galaxy. Some of the persistent pulsars are very luminous and some transient pulsars can reach very high luminosities like 10^37ergss^-1. On an average there is more than one bright transient at any instant. We expect the same to be true for M 31. In the proposed observation, we plan to detect pulsations in the already known persistent pulsar 3X J0043 and hopefully, discover some new pulsars with LAXPC.

Most of the massive merging clusters are host to cluster-scale diffuse radio sources termed as radio halos. Radio halos have been proposed to be generated by (re-)acceleration of fossil relativistic electrons in the ICM by MHD-turbulence injected during cluster mergers. Joint radio and X-ray studies are essential to study the radio halos and their origin. We propose X-ray observations of the galaxy cluster Abell 3535 in the Shapley supercluster which is an unusual ``low mass cluster with a candidate radio halo'' emission. We have deep radio observations with the MWA, GMRT and the JVLA for the cluster and propose Astrosat X-ray observations. The X-ray observations will be used to find the morphology of the intra-cluster medium and to study its luminosity and temperature. We propose an observation of 50ks with the SXT. Data from LAXPC will be used to find if there is hard X-ray emission associated with this cluster.

Cyclotron line variations with luminosity have been observed in transient Be HMXBs which conform to expected trends of correlation depending on source luminosity (Becker 2012). Apart from a weak correlation between luminosity and cyclotron line energy reported in Fürst (2014), persistent Supergiant HMXB systems (SgHMXBs) have not been studied systematically to note if such variations exist. We propose three observations of 15 kiloseconds each with ASTROSAT of a persistent SgHMXB (Cen X-3) with a large range of flux variations. This study will enable comparisons between wind fed SgHMXBs and disk accreting Be transients in terms of their cyclotron lines and how they are formed in the accretion column above the neutron star. Our proposal is of a monitoring kind to study variabilities with higher requested exposure times at different times and we cannot do the desired science with observations already done by ASTROSAT in GT phase.

The EGRET and Fermi observations reveal that a number of flat spectrum radio quasars (FSRQ) exhibit long term $\gamma$-ray variability. PKS~0208-512 is one such source which shows at least an order of magnitude lower $\gamma$-ray flux level during six years of Fermi operation in comparison to the averaged flux level detected by EGRET. Along with the long term variability, PKS~0208-512 also showed the short term variability (relatively much lower amplitude) in optical and X-ray region in the low $\gamma$-ray emission state. To understand the radiative process in sources at their low $\gamma$-ray activity state, observations in UV and soft X-ray band are crucial. Thus, we propose simultaneous observation of PKS~0208-512 with UVIT, SXT along with LAXPC and CZTI detectors on board ASTROSAT satellite which is essential to construct the broadband spectra of the source and to better understand the physical process responsible for such long term low $\gamma$-ray activity state.

LMC X-1 and LMC X-3 are the two persistent black hole binaries in the Large Magellanic Cloud. LMC X-1 is a high mass X-ray binary accreting from the wind of an O-type star, whereas LMC X-3 is a low mass X-ray binary accreting via Roche-lobe overflow of a B-type companion. Both the sources have unusual spectral behavior as compared to the other black hole binaries. LMC X-1 has never entered the hard state, whereas LMC X-3 has exhibited occasional prolonged excursions to the hard state. Study of both the sources with AstroSat will be helpful in their detailed spectral and timing studies. Therefore, observations of the two sources are proposed here, each with an exposure of 50 ks. AstroSat data will be of particular help in the detection of QPOs and their further detailed study for the black hole binary LMC X-1.

We propose a pilot study of Milky Way faint dwarf satellites using UVIT. Ultra faint dwarf satellite galaxies around Milky Way are thought to be the first galaxies that were formed in the universe. Recent, large photometric surveys were successful in detecting new faint satellite galaxies around Milky Way and partly alleviating the so called ”missing satellite problem”. However, very little is known about their formation epoch and star formation history and evolution. UV observations are useful probes of stellar populations that might have had different chemical history, through its additional sensitivity to probe helium abundance and metallicities, compared to optical colours. We propose here UV, visible and X-ray observations of Reticulum-II, one of the faint dwarf satellites and a dark matter dominated system. There were recent claims of gamma ray detection in Ret-II, as a signature of dark matter annihilation, hence any X-ray observations may be interesting.

We propose to commence monitoring observations of a bright variable AGN and to use the ASTROSAT instrument complement to unravel the complex behaviour of these objects with a view to elucidating the underlying physical conditions and geometry in the regions responsible for their optical to har X-ray emission

We propose to observe 4U1323-62 using SXT, LAXPC and CZTI for 25ks exposure. 4U1323-62 is a LMXB dipper with an orbital period of 2.94 hour which shows 1 Hz QPO and frequent thermonuclear bursts. The angle between the line-of sight and the rotational axis of the accretion disk is approximately 60 degrees. Due to the high inclination this source produces absorption lines which are useful to decipher the chemical, physical and kinematical properties of the accreting structure. Our aim is to observe this source over a wide range of X-ray energy (0.3-150) keV and study the broadband spectrum, timing properties such as QPOs, thermonuclear bursts and later do detail spectroscopic modelling. Such simultaneous broadband and spectral modelling has not done before. The large area and unprecedented time resolution of LAXPC and the soft X-Ray energy range will be our advantage over previous observations to understand the underlying physical processes.

We plan to obtain X-ray timing data to detect and model High-frequency Quasi-periodic oscillations (HFQPOs) in Black-hole binaries (BHBs). We have developed time series analysis tools like periodogram analysis, Multi-harmonic analysis of Variance, Wavelet analysis for QPO detection from light curves besides the Continuous-time Autoregressive Moving Average (CARMA) model in our analysis kit. Using Fourier expansion of the Doppler g-factor for the general case of a rotating object with geometric effects like Light bending, gravitational red-shift, frame dragging taken into account, we use models to fit light curves and address the 3:2 commensurability of HFQPOs in BHBs. Our targets are BHBs XTEJ1550-564, GROJ1655-40, H1743-322, XTEJ1650-500, 4U1630-47 with LAXPC to detect HFQPOs using this tool kit. Detection of QPOs will be used to validate our theoretical models.

We plan to obtain X-ray timing data to detect and model High-frequency Quasi-periodic oscillations (HFQPOs) in Black-hole binaries (BHBs). We have developed time series analysis tools like periodogram analysis, Multi-harmonic analysis of Variance, Wavelet analysis for QPO detection from light curves besides the Continuous-time Autoregressive Moving Average (CARMA) model in our analysis kit. Using Fourier expansion of the Doppler g-factor for the general case of a rotating object with geometric effects like Light bending, gravitational red-shift, frame dragging taken into account, we use models to fit light curves and address the 3:2 commensurability of HFQPOs in BHBs. Our targets are BHBs XTEJ1550-564, GROJ1655-40, H1743-322, XTEJ1650-500, 4U1630-47 with LAXPC to detect HFQPOs using this tool kit. Detection of QPOs will be used to validate our theoretical models.

We plan to obtain X-ray timing data to detect and model High-frequency Quasi-periodic oscillations (HFQPOs) in Black-hole binaries (BHBs). We have developed time series analysis tools like periodogram analysis, Multi-harmonic analysis of Variance, Wavelet analysis for QPO detection from light curves besides the Continuous-time Autoregressive Moving Average (CARMA) model in our analysis kit. Using Fourier expansion of the Doppler g-factor for the general case of a rotating object with geometric effects like Light bending, gravitational red-shift, frame dragging taken into account, we use models to fit light curves and address the 3:2 commensurability of HFQPOs in BHBs. Our targets are BHBs XTEJ1550-564, GROJ1655-40, H1743-322, XTEJ1650-500, 4U1630-47 with LAXPC to detect HFQPOs using this tool kit. Detection of QPOs will be used to validate our theoretical models.

We plan to obtain X-ray timing data to detect and model High-frequency Quasi-periodic oscillations (HFQPOs) in Black-hole binaries (BHBs). We have developed time series analysis tools like periodogram analysis, Multi-harmonic analysis of Variance, Wavelet analysis for QPO detection from light curves besides the Continuous-time Autoregressive Moving Average (CARMA) model in our analysis kit. Using Fourier expansion of the Doppler g-factor for the general case of a rotating object with geometric effects like Light bending, gravitational red-shift, frame dragging taken into account, we use models to fit light curves and address the 3:2 commensurability of HFQPOs in BHBs. Our targets are BHBs XTEJ1550-564, GROJ1655-40, H1743-322, XTEJ1650-500, 4U1630-47 with LAXPC to detect HFQPOs using this tool kit. Detection of QPOs will be used to validate our theoretical models.

We plan to obtain X-ray timing data to detect and model High-frequency Quasi-periodic oscillations (HFQPOs) in Black-hole binaries (BHBs). We have developed time series analysis tools like periodogram analysis, Multi-harmonic analysis of Variance, Wavelet analysis for QPO detection from light curves besides the Continuous-time Autoregressive Moving Average (CARMA) model in our analysis kit. Using Fourier expansion of the Doppler g-factor for the general case of a rotating object with geometric effects like Light bending, gravitational red-shift, frame dragging taken into account, we use models to fit light curves and address the 3:2 commensurability of HFQPOs in BHBs. Our targets are BHBs XTEJ1550-564, GROJ1655-40, H1743-322, XTEJ1650-500, 4U1630-47 with LAXPC to detect HFQPOs using this tool kit. Detection of QPOs will be used to validate our theoretical models.

We request observations of three distant, but bright flat spectrum radio quasars 3C 454.3 using all the multiwavelength instruments on-board the ASTROSAT. We propose for a single pointing observations of 40 ks for the source. The proposed observations will provide simultaneous spectral measurements in the UV, soft and hard X-ray bands for these highly luminous blazars, which will allow us to study the variations over a few minutes timescales. The X-ray emission process in FSRQs is largely uncertain with models advocating both Synchrotron-Self-Compton(SSC) and External Compton (EC) processes. A simultaneous coverage of spectral and temporal behaviour of broadband X-ray spectrum along with UV can be used to constrain the emission process in action. Specifically, in tandem with gamma-ray observations by Fermi, this can unravel the physics behind “Compton-dominance” by identifying the dominant external photon field in blazar environment.

We propose to survey three high Galactic latitude globular clusters, NGC 7492, NGC 4590 and NGC 5466. The dominant contribution of Ultraviolet (UV) light in these clusters of old stellar population is UV-bright objects such as hot WDs, hot post-AGB stars and blue horizontal branch stars (BHBs). High resolution of UVIT will be very useful in resolving the UV-bright objects and the more number UVIT filters will provide more color options to separate them out. The UV CMDs will enable us to understand the evolutionary stage of these objects and classify them. Measuring the UV colors, using the Kurucz model of stellar atmospheres and adopting the filter responses of UVIT, the effective temperature and metalicity of UV-bright stars can be determined. Knowing the distances of globular clusters, it will also be feasible to derive the absolute UV fluxes which are useful to compare their SEDs with model atmospheres.

We propose to survey three high Galactic latitude globular clusters, NGC 7492, NGC 4590 and NGC 5466. The dominant contribution of Ultraviolet (UV) light in these clusters of old stellar population is UV-bright objects such as hot WDs, hot post-AGB stars and blue horizontal branch stars (BHBs). High resolution of UVIT will be very useful in resolving the UV-bright objects and the more number UVIT filters will provide more color options to separate them out. The UV CMDs will enable us to understand the evolutionary stage of these objects and classify them. Measuring the UV colors, using the Kurucz model of stellar atmospheres and adopting the filter responses of UVIT, the effective temperature and metalicity of UV-bright stars can be determined. Knowing the distances of globular clusters, it will also be feasible to derive the absolute UV fluxes which are useful to compare their SEDs with model atmospheres.

We propose to survey three high Galactic latitude globular clusters, NGC 7492, NGC 4590 and NGC 5466. The dominant contribution of Ultraviolet (UV) light in these clusters of old stellar population is UV-bright objects such as hot WDs, hot post-AGB stars and blue horizontal branch stars (BHBs). High resolution of UVIT will be very useful in resolving the UV-bright objects and the more number UVIT filters will provide more color options to separate them out. The UV CMDs will enable us to understand the evolutionary stage of these objects and classify them. Measuring the UV colors, using the Kurucz model of stellar atmospheres and adopting the filter responses of UVIT, the effective temperature and metalicity of UV-bright stars can be determined. Knowing the distances of globular clusters, it will also be feasible to derive the absolute UV fluxes which are useful to compare their SEDs with model atmospheres.

We propose to carry out an in-depth X-ray, FUV and NUV study of a fast rotator CC Eri with rotation period 1.56 days. We intend to study the ighly time-resolved correlation of upper chromospheric and coronal activity indicators and to study the rotational modulation of its X-ray, FUV and NUV fluxes. These proposed observations will also allow us to understand the dynamic behavior of the corona, which is found to be strongly related to the fluorescence of the photospheric materials. Furthermore, the proposed observations will yield insight into the nature of the associated magnetic dynamos.

Globular Clusters (GCs) house exotic stellar populations and are the only sites where the products of direct collision of stars (Blue Straggler stars, BSS) are found. GCs also have accreting binaries, WDs and Horizontal branch stars, which are all bright in the UV. In the UV, all these stars stand out from the swamp of the cooler main-sequence stars and red giants. Our simulations suggest that the colour-magnitude diagrams using UVIT filters create definite diagnostic regions which can be used to detect and identify these systems. Exploiting the resolution and filter system of the UVIT, we plan to derive the multi-wavelength SEDs and estimate the fundamental properties such as mass, temperature and Luminosity. NGC 1904 is one such cluster with many UV bright stars located in the cluster.

We propose to commence monitoring observations of a bright variable AGN and to use the ASTROSAT instrument complement to unravel the complex behaviour of these objects with a view to elucidating the underlying physical conditions and geometry in the regions responsible for their optical to har X-ray emission

We propose two Astrosat observations of the transient low mass X-ray binary MXB 1658-298 during the last 45 days of the Astrsoat cycle AO-2. MXB 1658-298 has an orbital period of 7.1 hr and is one of the very few eclipsing LMXBs that allows a study of its orbital period evolution. From archival observations of this source during the previous two outbursts, we have found it to have unusual orbital evolution. The proposed observations will allow us to extend the baseline for the orbital evolution study and help probe the origin of its unusual character. It is also a source that shows thermonuclear bursts and burst oscillations at ~1.8 ms. We will probe the burst oscillation phenomena in high energies and also carry out thermonuclear burst spectroscopy to measure the radius of the neutron star.

Black hole X-ray binaries cycle through different accretion states on timescales of days to months, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous observations across the electromagnetic spectrum are the optimal tool that exposes this view. However, strictly simultaneous radio through broad-band X-ray observations have been achieved in only a few X-ray binary outbursts. We request three 20 ks epochs of ASTROSAT (LAXPC/SXT/CZTI) observations of GX~339-4. We will trigger one sequence of 15-day monitoring over three epochs, for which we will coordinate multi-wavelength coverage, to measure the evolving broad-band spectral energy distributions (SEDs) during either the rising-hard and decaying-hard accretion states. We will determine how the evolving accretion properties (derived from X-ray timing and fitting models to X-ray spectra) are connected to the evolving jet properties (derived from broad-band SED fits that constrain, for example, the conditions where the electrons are first accelerated).

IGR J16493-4348 is a wind-fed eclipsing X-ray binary that hosts a neutron star as the compact object. We propose 40 ks of observation of IGR J16493-4348 in order to achieve the following goals: (i) Broad-band spectroscopy to constrain the continuum parameters, (ii) Study the soft and hard X-ray pulse profiles which has never been reported earlier for this source, (iii) Search for cyclotron line speculated to be at 30 keV from earlier observations of very limited statistics. With an unmatched combination of large effective area, high time resolution, and good spectral resolution of LAXPC, such broad-band spectral as well as their timing properties can be extensively carried out.

We propose to map the UV emission around dual nuclei in late stage galaxy mergers and interacting systems. Mergers can trigger bursts of star-formation and nuclear activity in galaxies. This can result in dual AGN and AGN+star-forming nuclei in the merging galaxies. Our targets have been observed by GALEX but not with the Hubble Space Telescope (HST) UVIS camera. The higher spatial resolution of UVIT compared to GALEX will help us resolve the dual cores and study the disk star-formation triggered by the merging process. Our targets are all low redshift, UV bright sources. We will confirm the nature of the double cores, map the associated star-formation, estimate star-formation rates and its correlation with the different types of nuclei. Not much is known about the UV emission from dual AGN/starburst nuclei; hence UVIT observations will be an important step for understanding galaxy mergers.

We propose to map the UV emission around dual nuclei in late stage galaxy mergers and interacting systems. Mergers can trigger bursts of star-formation and nuclear activity in galaxies. This can result in dual AGN and AGN+star-forming nuclei in the merging galaxies. Our targets have been observed by GALEX but not with the Hubble Space Telescope (HST) UVIS camera. The higher spatial resolution of UVIT compared to GALEX will help us resolve the dual cores and study the disk star-formation triggered by the merging process. Our targets are all low redshift, UV bright sources. We will confirm the nature of the double cores, map the associated star-formation, estimate star-formation rates and its correlation with the different types of nuclei. Not much is known about the UV emission from dual AGN/starburst nuclei; hence UVIT observations will be an important step for understanding galaxy mergers.

We propose to map the UV emission around dual nuclei in late stage galaxy mergers and interacting systems. Mergers can trigger bursts of star-formation and nuclear activity in galaxies. This can result in dual AGN and AGN+star-forming nuclei in the merging galaxies. Our targets have been observed by GALEX but not with the Hubble Space Telescope (HST) UVIS camera. The higher spatial resolution of UVIT compared to GALEX will help us resolve the dual cores and study the disk star-formation triggered by the merging process. Our targets are all low redshift, UV bright sources. We will confirm the nature of the double cores, map the associated star-formation, estimate star-formation rates and its correlation with the different types of nuclei. Not much is known about the UV emission from dual AGN/starburst nuclei; hence UVIT observations will be an important step for understanding galaxy mergers.

We propose to carry out simultaneous ultra violet and X-ray observations of a group of chemically peculiar giant stars identified to be in a binary system. These samples have been selected from the Henize samples of S stars which shows peculiarities in their optical spectra. These objects are identified with H a emission and radial velocity variation thus they are expected to show the symbiotic activity. Possible detection of ultraviolet flux and x-ray emission from these binary systems will help to determine the parameters of the companion accurately to have a better idea about the companion and the nature of the accretion process onto the companion star thereby drawing the connection between the symbiotic binaries and extrinsic S stars.

The presence of very hot stars having short-lived stages of stellar evolution like white dwarfs and blue straggler stars etc in the old (1 Gyr) galactic open star cluster provides a unique opportunity to probe their formation histories. For this, we propose to observe 2 old open clusters namely Be 67 and King 2 using 2 far UV and 2 near UV filters of UVIT of ASTROSAT payload. A total of 10.9 K seconds observing time is needed.These space based valuable observations along with already available ground based photometric data will be used to construct spectral energy distribution of very hot stars over a long wavelength range from UV to near-IR. Such results along with simultaneous X-ray observations shall provide insight in the formation processes of white dwarfs (WDs), blue stragglers stars (BSS) and compact binaries etc.

The presence of very hot stars having short-lived stages of stellar evolution like white dwarfs and blue straggler stars etc in the old (1 Gyr) galactic open star cluster provides a unique opportunity to probe their formation histories. For this, we propose to observe 2 old open clusters namely Be 67 and King 2 using 2 far UV and 2 near UV filters of UVIT of ASTROSAT payload. A total of 10.9 K seconds observing time is needed.These space based valuable observations along with already available ground based photometric data will be used to construct spectral energy distribution of very hot stars over a long wavelength range from UV to near-IR. Such results along with simultaneous X-ray observations shall provide insight in the formation processes of white dwarfs (WDs), blue stragglers stars (BSS) and compact binaries etc.

The mechanism by which disc is formed is classical Be stars, known as ‘Be phenomenon’, is one of the open puzzles in stellar research (Rivinius et al. 2013). One of the often suggested mechanisms is the role of an ‘invisible’ companion in the formation of this disc (Porter & Rivinius 2003). By ‘invisible’ companion we mean the companion whose presence is not easily assessed from continuum emission or spectral features in optical/infrared. They make their presence felt in the far-UV and X-ray region of the electromagnetic spectrum. Our proposal is to search for the elusive Be binary systems with white-dwarf (WD) or subdwarf O-type star (sdO or helium star) being the companion to Be star. However, no Be-WD system is detected till now and only a few (about 4) binaries belonging to Be-sdO category. Observations with UVIT and SXT are proposed to identify the hidden companions associated with Be stars.

The mechanism by which disc is formed is classical Be stars, known as ‘Be phenomenon’, is one of the open puzzles in stellar research (Rivinius et al. 2013). One of the often suggested mechanisms is the role of an ‘invisible’ companion in the formation of this disc (Porter & Rivinius 2003). By ‘invisible’ companion we mean the companion whose presence is not easily assessed from continuum emission or spectral features in optical/infrared. They make their presence felt in the far-UV and X-ray region of the electromagnetic spectrum. Our proposal is to search for the elusive Be binary systems with white-dwarf (WD) or subdwarf O-type star (sdO or helium star) being the companion to Be star. However, no Be-WD system is detected till now and only a few (about 4) binaries belonging to Be-sdO category. Observations with UVIT and SXT are proposed to identify the hidden companions associated with Be stars.

The mechanism by which disc is formed is classical Be stars, known as ‘Be phenomenon’, is one of the open puzzles in stellar research (Rivinius et al. 2013). One of the often suggested mechanisms is the role of an ‘invisible’ companion in the formation of this disc (Porter & Rivinius 2003). By ‘invisible’ companion we mean the companion whose presence is not easily assessed from continuum emission or spectral features in optical/infrared. They make their presence felt in the far-UV and X-ray region of the electromagnetic spectrum. Our proposal is to search for the elusive Be binary systems with white-dwarf (WD) or subdwarf O-type star (sdO or helium star) being the companion to Be star. However, no Be-WD system is detected till now and only a few (about 4) binaries belonging to Be-sdO category. Observations with UVIT and SXT are proposed to identify the hidden companions associated with Be stars.

We propose to observe the spectral energy distribution (SED) of a small sample of bare active galactic nuclei (AGN) for a total of 120ks (4 x 30ks). The simultaneous broadband coverage provided by ASTROSAT and the low level of extinction in these AGN make it possible to study the multicomponent spectrum of the black hole accretion disc system in great detail. We will be able to model the thermal disc component, the primary X-ray source, and the reflected emission simultaneously; thereby testing the nature of the emission processes and origin of the ‘soft-excess' (e.g. blurred reflection or Comptonisation). We will take first steps searching for suspected correlations between the X-ray weakness of AGN and the strength of the primary emission reflected off the accretion disc. We will also begin searching for differences between typical broad line Seyfert 1s and so called narrow-line Seyfert 1s that exhibit higher Eddington accretion rates.

We propose to observe the spectral energy distribution (SED) of a small sample of bare active galactic nuclei (AGN) for a total of 120ks (4 x 30ks). The simultaneous broadband coverage provided by ASTROSAT and the low level of extinction in these AGN make it possible to study the multicomponent spectrum of the black hole accretion disc system in great detail. We will be able to model the thermal disc component, the primary X-ray source, and the reflected emission simultaneously; thereby testing the nature of the emission processes and origin of the ‘soft-excess' (e.g. blurred reflection or Comptonisation). We will take first steps searching for suspected correlations between the X-ray weakness of AGN and the strength of the primary emission reflected off the accretion disc. We will also begin searching for differences between typical broad line Seyfert 1s and so called narrow-line Seyfert 1s that exhibit higher Eddington accretion rates.

We are requesting one 10 ksec exposures of the peculiar candidate ultra-compact X-ray binary (UCXB) 4U 0614+09. The orbital period is likely to be short, but is not accurately known, with tentative claims spanning the range of 15-45 min. However, unlike other UCXBs, type-I hard X-rays bursts and a puzzling optical/X-ray anti-correlation have been observed. With simultaneous AstroSat and South African+Devasthal (optical) telescopes, our primary goal is to measure the orbital period accurately by searching for periodic variations in both photometric and spectroscopic data, and confirm the nature of the source. Additionally we will search for X-ray bursts, carry out broadband X-ray spectro-timing analyses, and also have be able to coordinate with infrared and radio observations to understand the nature of possible non-thermal multi-wavelength emission.

We propose a 19.5 ks SXT effective exposure of BHC MAXI J1305-704 using LAXPC & SXT instruments on-board the AstroSat satellite. The source is a transient LMXB discovered by MAXI and it continues to be persistent. Variable dips of ~ 1.5 hr, 2.7 hr and two types of variabilities in the timescales of 9.7 hr are observed from this source. During dips significant increase in absorp- tion and spectral hardening are also reported. The broadband spectral studies by Swift, Suzaku, & Chandra observatories indicate the BH nature of the source. But, surprisingly, lack of variability at 50 s timescales disagree with its BH nature. As the source was detected during 2012 April 9, it was not observed by RXTE. LAXPC is an ideal instrument to study energy dependent timing variabilities in 0.3-80 keV energy band, will confirm the BH nature of the source which is unprecedented for MAXI J1305-704.

We request for monitoring observations, 20ks exposure every 15 days throughout the 6-month observing period, of the hard X-ray brightest type 1 Seyfert galaxy IC4329A. This AGN with a black hole mass of 1.2e8M_sun is strongly variable on weeks-to-months timescale in the Optical/UV and X-ray bands. The proposed observations will track the changes in the physical properties (i.e., the temperature and optical depth) of the hot corona, for the first time in the history of AGN research. This will help us to determine the nature of the primary X-ray source. We will also determine the seed photons for the Comptonisation by cross-correlating the absorption-free hard X-rays with the soft X-rays and different UVIT bands. We will investigate the connection between the changes in the physical properties of the corona and the UV variations, and also the inter-band UV/X-ray correlations, and study the coupling between the disk and the hot corona.

%latex%XTE J1701-407 is a transient low mass X-ray binary (LMXB) in which kHz QPOs have been detected with very high rms ($\sim$30 \%) and large difference in the frequency of the twin kHz QPOs ($\Delta \nu \approx 380$ Hz). The source has a luminosity $\sim$0.01$L_{EDD}$ and its rms-energy relation has not been well constrained nor has the evolution of $\Delta \nu$ with the drift in the frequency of kHz QPOs. We propose to monitor this source with 6 ks observations with AstroSat/LAXPC as the primary instrument during its next outburst to understand better the rms- energy relation and evolution of $\Delta \nu$ with drift in the frequency of the kHz QPO.

We propose anticipated target of opportunity ASTROSAT observations of the five gamma-ray bright flat spectrum radio quasars (FSRQs) with a goal to monitor and understand the spectral transition, constrain, via the variability, the radiative mechanisms and the size and location of the emission regions. To achieve these objectives, we request ToO monitoring, whenever any of the five FSRQs undergo large magnitude hard gamma-ray flares with photon index <2 and daily binned gamma-ray flux exceeding 5 × 10^-6 ph/cm^2/s . By applying a leptonic and lepto-hadronic emission modeling approach, we will be able to constrain the underlying factors causing spectral hardening observed at gamma-rays, with or without a counterpart at optical-UV and X-ray energies.

We propose anticipated target of opportunity ASTROSAT observations of the five gamma-ray bright flat spectrum radio quasars (FSRQs) with a goal to monitor and understand the spectral transition, constrain, via the variability, the radiative mechanisms and the size and location of the emission regions. To achieve these objectives, we request ToO monitoring, whenever any of the five FSRQs undergo large magnitude hard gamma-ray flares with photon index <2 and daily binned gamma-ray flux exceeding 5 × 10^-6 ph/cm^2/s . By applying a leptonic and lepto-hadronic emission modeling approach, we will be able to constrain the underlying factors causing spectral hardening observed at gamma-rays, with or without a counterpart at optical-UV and X-ray energies.

?102-5M¿), or have super- Eddington accretion. In 2014, NuSTAR reported the detection of pulsations from the ULX M82X–2, supporting a highly accreting neutron star/magnetar origin. But so far, such pulsations have been observed on only one occasion. The brighter ULX in the field, M82X–? 1000M¿?20 ks, which will allow us to search for signals using the larger effective area of LAXPC as compared to NuSTAR, having the potential for far reaching breakthrough in this field.

We propose to carry out the X-ray, FUV and NUV astrosat observation of two narrow-line Seyfert 1 galaxies (NLS1) which are also target of SDSS reverberation mapping(RM) campaign. From the analysis of their multi-epoch SDSS spectra suggest, one belong to sub-class with significant variability and another with non-significant variability based on their SDSS spectra of about 30 epoch over 200 days duration. To understand the physical parameter governing this difference in these two possible sub-classes, spectral energy distribution (SED) based on simultaneous multi-waveband observation with astrosat will be very rewarding, as their BH mass are accurately determined from SDSS RM and optical follow-up will be done with ARIES 3.6m Devasthal Optical telescope. Further, any difference if found in the X-ray and UV SED of these two sources will also give important clue about the presence/absence of warm absorber in these two classes for further investigation with larger statistical sample.

We propose to carry out the X-ray, FUV and NUV astrosat observation of two narrow-line Seyfert 1 galaxies (NLS1) which are also target of SDSS reverberation mapping(RM) campaign. From the analysis of their multi-epoch SDSS spectra suggest, one belong to sub-class with significant variability and another with non-significant variability based on their SDSS spectra of about 30 epoch over 200 days duration. To understand the physical parameter governing this difference in these two possible sub-classes, spectral energy distribution (SED) based on simultaneous multi-waveband observation with astrosat will be very rewarding, as their BH mass are accurately determined from SDSS RM and optical follow-up will be done with ARIES 3.6m Devasthal Optical telescope. Further, any difference if found in the X-ray and UV SED of these two sources will also give important clue about the presence/absence of warm absorber in these two classes for further investigation with larger statistical sample.

Blue Horizontal Branch (HB) stars observed in globular clusters (GCs) have very high temperature (Teff > 20000 K), which make them strong UV emitter. These HB stars have lost a substantial amount of mass in the RGB phase, and hence significantly affect the morphology and metallicity of GCs. Study of HB stars will help us to understand the evolution of GCs. HB stars can be identified by combinations of UV and optical color-color and color-magnitude diagrams. GCs in the Milky Way are better studied compared to other galaxies. Earlier attempts have been made to study GCs by a few authors using Galaxy Evolution and Explorer (GALEX) data. But due to poorer spatial resolution of GALEX their sample might not be complete. Hence, we want to perform study of three GCs in the M31 using UVIT on board AstroSat for detailed study of HB stars and understand their evolution.

Blue Horizontal Branch (HB) stars observed in globular clusters (GCs) have very high temperature (Teff > 20000 K), which make them strong UV emitter. These HB stars have lost a substantial amount of mass in the RGB phase, and hence significantly affect the morphology and metallicity of GCs. Study of HB stars will help us to understand the evolution of GCs. HB stars can be identified by combinations of UV and optical color-color and color-magnitude diagrams. GCs in the Milky Way are better studied compared to other galaxies. Earlier attempts have been made to study GCs by a few authors using Galaxy Evolution and Explorer (GALEX) data. But due to poorer spatial resolution of GALEX their sample might not be complete. Hence, we want to perform study of three GCs in the M31 using UVIT on board AstroSat for detailed study of HB stars and understand their evolution.

Blue Horizontal Branch (HB) stars observed in globular clusters (GCs) have very high temperature (Teff > 20000 K), which make them strong UV emitter. These HB stars have lost a substantial amount of mass in the RGB phase, and hence significantly affect the morphology and metallicity of GCs. Study of HB stars will help us to understand the evolution of GCs. HB stars can be identified by combinations of UV and optical color-color and color-magnitude diagrams. GCs in the Milky Way are better studied compared to other galaxies. Earlier attempts have been made to study GCs by a few authors using Galaxy Evolution and Explorer (GALEX) data. But due to poorer spatial resolution of GALEX their sample might not be complete. Hence, we want to perform study of three GCs in the M31 using UVIT on board AstroSat for detailed study of HB stars and understand their evolution.

We propose 40 ks observation of the high mass X-ray binary pulsar 4U 1538-522 with ASTROSAT. The source exhibits variability on short time scales in the form of dips and flares and spectra exhibits two cyclotron lines at ~22 and ~47 keV. With this proposal we plan to achieve the following goals : i) Measure energy and intensity dependent pulse profiles especially in the hard X-rays to study the beaming geometry and map its change with luminosity. ii) Study variation of hydrogen column density as a function of orbital phase and understand wind pattern. iii) Perform broad-band spectroscopy (SXT+LAXPC+CZTI) to constrain continuum parameters and accurately measure the CRSF. iv) Study the pulse phase dependence of the fundamental and first harmonic. v) With the excellent time resolution and broadband capability of LAXPC, this will be good opportunity to compare simultaneously broadband energy and power density spectra at different intensity levels.

Blazars are very well-known to exhibit flux and polarization variability from radio to TeV energies. A variable emission over diverse timescales help to understand AGN emission processes, in particular, blazars.The distinctive feature of blazar emission is high and variable polarization in radio and optical bands, which is associated with synchrotron emission originated at much lower energy. A continuous optical PA rotation during active stages are now known to be associated with high energy gamma-ray events, which gives an insight to magnetic field configuration and various emission mechanisms. We aim for a simultaneous multi-wavelength observations ASTROSAT mission, along with quasi-simultaneous ground-based polarimetry to study polarization properties in blazars during low and high flux states at diverse energies. Here, we propose for the monitoring of HBL 1ES 1959+650 at two different epochs of 12ks each during AO-01. The present study will certainly contribute towards general understanding of physical processes responsible in blazars.

Her X-1 is to be intensely observed by UVIT, SXT, LAXPC, and CZTI instruments for one full binary during main high state. The neutron star illuminates the companion star, accretion disk, accretion stream and disk corona. This causes detectable X-rays and UV from these structures which are orbital phase dependent. Modelling of the orbital-phase dependent light curves in multiple energy band will be used to map these structures in the binary system. Time delays between the pulsations in the different energy bands will enable extraction of line-of-sight travel time delays and distances. The expected scientific results are: i) to obtain the geometry of the X-ray heating of HZ Her, the accretion disk, the accretion stream and the corona; and ii) to precisely determine the inclination of the binary. The improved system inclination will allow precise binary parameters and result in a well-determined neutron star mass.

The neutron star SAX J1808.4-3658 (hereafter J1808) was the first discovered accreting millisecond period X-ray pulsar (AMXP). J1808 is a "Rosetta Stone" system showing the evolutionary role of accretion in spinning neutron stars up to millisecond (ms) spin periods in low mass X-ray binaries (LMXBs) to form ms radio pulsars. The observed X-ray pulsations originate from the neutron star's surface, allowing pulse-shape analyses to determine the star's mass and radius, which could allow the equation of state of ultra-dense nuclear matter to be constrained. The pulsations are only visible when the AMXP is in a bright state (outburst). We propose to observe J1808 for 40ks during its next outburst, allowing us to measure its spectrum and pulse shapes. These will be used to determine the neutron star's mass, radius, and orbital period changes, leading to better understanding of the properties of neutron stars and accretion in LMXBs.

The blue straggler stars (BSS) are main-sequence stars, which have evaded stellar evolution by acquiring mass while on the main-sequence. Primary mechanisms suggested for BSS formation in open clusters are (1) mass transfer from a binary and (2) merger of binaries. Gosnell et al. (2015) found that about 67% of blue stragglers are formed via mass transfer in the old open cluster NGC 188, by detecting WD companions to 7 BSS using the HST FUV observations. Accurate estimation of FUV flux is the main requirement to detect as well as estimate the temperature of WDs, in a BSS+WD binary. In the case of merged binaries, we do not expect to see a binary star or a WD as a companion. We plan to study a metal rich dense cluster (NGC 6791, with 50\% BSS in binaries) and a metal poor and moderately rich cluster (NG 7789, with identified contact binaries).

The blue straggler stars (BSS) are main-sequence stars, which have evaded stellar evolution by acquiring mass while on the main-sequence. Primary mechanisms suggested for BSS formation in open clusters are (1) mass transfer from a binary and (2) merger of binaries. Gosnell et al. (2015) found that about 67% of blue stragglers are formed via mass transfer in the old open cluster NGC 188, by detecting WD companions to 7 BSS using the HST FUV observations. Accurate estimation of FUV flux is the main requirement to detect as well as estimate the temperature of WDs, in a BSS+WD binary. In the case of merged binaries, we do not expect to see a binary star or a WD as a companion. We plan to study a metal rich dense cluster (NGC 6791, with 50\% BSS in binaries) and a metal poor and moderately rich cluster (NG 7789, with identified contact binaries).

IGR J16318-4848 is a Supergiant HMXB (sgHMXB) system with the highest known line of sight absorption column density. This absorption column is mostly local to the source and reprocessing of the source X-rays from this medium causes iron and nickel lines with the highest known equivalent width among X-ray binaries to be seen in its spectrum. The source has shown strong signatures of an ~ 80 day orbital modulation in its hard X-ray intensity (Jain 2009) as well as variations in the line flux and equivalent widths (Ibarra 2007). We propose to monitor the source luminosity and line equivalent width in different phases of its binary orbit with ASTROSAT (8 observations of 6 ks in SXT each). This will allow us to probe the relation between the luminosity changes, line flux variations and orbital phase and possibly help us understand the reason behind the large flux modulations in this source.

We propose to observe the UV emission from the low luminosity stellar disks of eight spiral galaxies that have extended ultraviolet (XUV) disks. Our targets have all been detected by GALEX. They are all nearby spirals that we have selected based on their UV luminosity. XUV galaxies show filamentary or diffuse star formation well beyond their optical disks, in regions where the disk surface density lies below the threshold for star formation. GALEX found that 30% of spiral galaxies have XUV disks. The star formation is thought to be triggered by gas accretion from nearby clouds, galaxies or the intergalactic medium. In this study we will investigate the nature of XUV disk star formation, estimate its rate and morphology. The high sensitivity of UVIT will help isolate the star forming knots, image the UV disks and search for signatures of gas accretion.

We propose to observe the UV emission from the low luminosity stellar disks of eight spiral galaxies that have extended ultraviolet (XUV) disks. Our targets have all been detected by GALEX. They are all nearby spirals that we have selected based on their UV luminosity. XUV galaxies show filamentary or diffuse star formation well beyond their optical disks, in regions where the disk surface density lies below the threshold for star formation. GALEX found that 30% of spiral galaxies have XUV disks. The star formation is thought to be triggered by gas accretion from nearby clouds, galaxies or the intergalactic medium. In this study we will investigate the nature of XUV disk star formation, estimate its rate and morphology. The high sensitivity of UVIT will help isolate the star forming knots, image the UV disks and search for signatures of gas accretion.

The nature of the ultra-dense matter in neutron stars remains enigmatic and there is still a wide variety of possible internal compositions. Obtaining accurate radii and masses for neutron stars will allow to distinguish between these equations of state. We have suggested a powerful way to constrain both neutron star radii and masses by combining a measure of the inner disk radius from broad iron emission lines and the frequency of kHz quasi-periodic brightness oscillations (QPOs). However, this method only works if both phenomena originate from the same part of the disk. Here, we propose 30 ks observations of each of the neutron star low-mass X-ray binaries GX 349+2 and GX 340+0 to simultaneously obtain an accurate measure of the inner disk radius from broadband spectroscopy and the kHz QPO frequency from timing.

Our goal is to test the hypothesis that AGN feedback mechanisms that are required to preserve scaling relationships of supermassive black hole across cosmic time, leave their footprints on the ionization structure and star formation in their nuclear environments in the nearby universe. We propose a pilot study of six z~0 active galaxies for imaging with ASTROSAT UVIT and SXT. These galaxies are hand-picked from a large sample of nearby southern AGN which we are currently investigating with an optical integral field unit (WiFeS) and radio interferometry (GMRT and ATCA). We seek to establish (or otherwise) connections between the ionization structure of the nuclear regions, the synchrotron jets, the hot ionized gas driven by the AGN, the distribution of star formation regions and extinction structure in the host, the abundance gradient across the host and the kinematics of the extended narrow-emission-line regions. We request 90 kiloseconds.

Our goal is to investigate the physics of relativistic synchrotron jets launched by accreting supermassive black holes (i.e., AGN), within the framework of the Blazar Divide. We propose monitoring the chromaticity of the variability of three prioritized LAX P C -bright, UVIT-safe AGN target fields, mildly time-constrained (~30 ± 10day cadence) using the full multi-wavelength capability of ASTROSAT and LAXPC as the primary instrument. We will harness the Whole Earth Blazar Telescope for quasi-simultaneous ground-based observations, covering optical/IR/radio photometry, optical/radio (uGMRT) polarimetry, and optical spectroscopy, and also add co-epochal Fermi data. The AGN span a range of power, the ratio of nuclear-to-host galaxy and inverse-Compton dominance. We request 47ksecs/epoch each (~4 AO3 epochs) with LAXPC, SXT, CZTI and UVIT, totaling 188ksecs. We will also examine the CZTI data in order to inform future proposals.

Variability on different timescales throughout the EM spectrum is a key characteristic of AGN. AGN show strong variability in the optical-UV-X-ray wavelengths and these are often inter-connected. Using the simultaneous multiwavelength observational facility of ASTROSAT we plan to carry out a detailed study of Mrk 110, an NLS1 galaxy highly variable in the optical/UV and X-ray bands. We propose for a multiwavelength monitoring observation of Mrk 110 on 4 occasions, each separated by 15 days. We request to observe the source for an individual exposure time of 40 ks with SXT (primary instrument), simultaneously with LAXPC and UVIT. The study will help us to understand the relationship between the optical-UV-X-ray emission mechanisms, and the geometry of the emitting regions. Furthermore, a broadband SED modelling of the source, by including the IR data, can draw possible correlations between different physical parameters like Eddington ratio, luminosities, photon index and torus covering factor.

We propose Astrosat observations of a nearby active super flaring star star DG CVn to test the intrinsic flare X-ray emission and its relation to the other layers of atmosphere. Astrosat’s capability to observe such source in simultaneous multi-wavelengths is a powerful tool to understand these activities and their inter-relationship. Our target is an eclipsing binary found with an orbital period of ~0.28 days. Such binary systems are of tremendous importance for astrophysics at large, since they allow precise determinations of stellar masses and radii, but also for stellar activity research, since such systems probe the upper end of the activity scale. We propose to use Astrosat for a pilot study such a short period low-mass eclipsing binaries to explore their potential for detailed X-ray follow-up studies. The proposed observations will also yield insight into the nature of the associated magnetic dynamos.

4U 1735-44 is a low mass X-ray binary hosting a neutron star and a low mass companion star and its characteristic behavior in color-color diagram has classified the object as an atoll source. We propose a 50 ks AstroSat observation of the system with LAXPC as a primary instrument. The data will be used to study detailed spectral and timing properties of the system including time lags as a function of energy and frequency, Coherence and flux-resolved spectroscopy.

We propose to study the UV extinction and dust properties in M31 galaxy. In AO3 cycle we plan to observe few hot stars of different E(B-V) values in selected regions across M31 in FUV and NUV filter bands of UVIT in order to study variations of UV extinction. UV extinction properties are very sensitive to various physical parameters of dust and vary even when no changes are present in optical region. We plan to use B15 filter which is devised to measure the strength of the 2200\AA band. we also plan to observe previously spectroscopically studied objects in M31 for calibration and later systematically study various regions in M 31 of different environments. Stars with low and high reddening are planned to be studied differentially. M 31 provides an environment to study hot O and B star bright enough not to saturate UVIT detectors.

We propose to study the UV extinction and dust properties in M31 galaxy. In AO3 cycle we plan to observe few hot stars of different E(B-V) values in selected regions across M31 in FUV and NUV filter bands of UVIT in order to study variations of UV extinction. UV extinction properties are very sensitive to various physical parameters of dust and vary even when no changes are present in optical region. We plan to use B15 filter which is devised to measure the strength of the 2200\AA band. we also plan to observe previously spectroscopically studied objects in M31 for calibration and later systematically study various regions in M 31 of different environments. Stars with low and high reddening are planned to be studied differentially. M 31 provides an environment to study hot O and B star bright enough not to saturate UVIT detectors.

We propose 50 ks X-ray observations of Proxima Centauri with Astrosat to measure a high-resolution irradiation spectrum and, thus, to assess the habitability of the orbiting exoplanet. Our upcoming, very deep observations of Proxima Centauri with Chandra grating , HST along with the Astrosat’s SXT will provide us a great opportunity to obtain simultaneous coverage at X-ray and UV wavelengths. The LETG is generally used in combination with HRC-S a detector without any energy resolution, hence, the zeroth order LETGS has no energy resolution. The resolution and sensitivity at high energies can be accessed only from Astrosat’s SXT, since the resolution of the LETGS at higher energies gets worse. Astrosat would really be a very good complement to Chandra. Our Astrosat, Chandra LETG and HST UV data allows us to reconstruct a high resolution spectral energy distribution including EUV regime and, thus, a reference irradiation spectrum.

We propose a 50 ks ASTROSAT observation of the neutron star low-mass X-ray binary IGR J17062–6143, which persistently accretes at a very low luminosity of ~0.1% of the Eddington limit. Our main aim is to obtain simultaneous optical to hard X-ray coverage to gain insight into the accretion morphology in this object. This study will further our knowledge about low-level accretion flows in neutron star low-mass X-ray binaries, particularly in a regime that is difficult to capture with transient sources. Furthermore, it allows us to test different ideas for the nature of neutron stars that accrete at very low rates for several years.

We propose to continue monitoring observations of this bright variable AGN and to use the ASTROSAT instrument complement to unravel the complex behaviour of these objects with a view to elucidating the underlying physical conditions and geometry in the regions responsible for their optical to har X-ray emission

We propose to continue monitoring observations of bright variable AGN and to use the ASTROSAT instrument complement to unravel the complex behaviour of these objects with a view to elucidating the underlying physical conditions and geometry in the regions responsible for their optical to hard X-ray emission

We propose to study the persistent microquasar GRS 1758-258 for a total exposure of 60 ksec using SXT, LAXPC, CZTI and UVIT on-board AstroSat. SXT will be considered as the primary instrument. We plan to monitor the source during three epochs with continuous exposure of 20 ksec for each of the observations. Our previous proposal for AstroSat observation in AO2 (ID : AO2-077) for this source was performed during the period when the source had transited to its dim soft state as observed by INTEGRAL and SWIFT observations. During the period of AO3, we expect that the source will exhibit spectral and temporal variabilities, and to do a comparative study with our previous observation from AO2. Finally, we intend to diagnose the multi-wavelength characteristics of the source by means of a monitoring proposal through simultaneous observations in Radio and Optical bands.

We are proposing 50 ks effective exposure of the Be/X-ray binary pulsar SWIFT J1626.6-5156 using SXT, LAXPC & CZTI instruments onboard AstroSat satellite. Source is famous for its flux variability on time scale of a few sec, cyclotron line variability & a spin-up rate of 1.3062±0.0017x10^-12 Hz/s. These features are observed by RXTE/PCA, limited to ~25 keV. LAXPC as primary instrument with its wide energy coverage 3-80 keV will help in confirming ~18 keV cyclotron line feature of the source. High time resolution capabilities of LAXPC will enable more precise estimate of spin period during its spin up state, possible detection of QPOs & energy dependent timing studies during spin up, flaring/non-flaring states. The source may not have SXT pileup issues depending on the spectral state in which the source will be observed. We propose to study pulse phase, orbit & luminosity dependence of cyclotron line variability & its harmonics.

Black hole X-ray binaries cycle through different accretion states on timescales of days to months, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous observations across the electromagnetic spectrum are the optimal tool that exposes this view. However, strictly simultaneous radio through broad-band X-ray observations have been achieved in only a few X-ray binary outbursts. We request six 20 ks epochs of ASTROSAT (LAXPC/SXT/CZTI) observations of GX~339-4. We will trigger two sequences of 15-day monitoring over three epochs each, for which we will coordinate multi-wavelength coverage, to measure the evolving broad-band spectral energy distributions (SEDs) during the rising-hard and decaying-hard accretion states. We will determine how the evolving accretion properties (derived from X-ray timing and fitting models to X-ray spectra) are connected to the evolving jet properties (derived from broad-band SED fits that constrain, for example, the conditions where the electrons are first accelerated).

Black hole X-ray binaries cycle through different accretion states on timescales of days to months, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous observations across the electromagnetic spectrum are the optimal tool that exposes this view. However, strictly simultaneous radio through broad-band X-ray observations have been achieved in only a few X-ray binary outbursts. We request six 20 ks epochs of ASTROSAT (LAXPC/SXT/CZTI) observations of GX~339-4. We will trigger two sequences of 15-day monitoring over three epochs each, for which we will coordinate multi-wavelength coverage, to measure the evolving broad-band spectral energy distributions (SEDs) during the rising-hard and decaying-hard accretion states. We will determine how the evolving accretion properties (derived from X-ray timing and fitting models to X-ray spectra) are connected to the evolving jet properties (derived from broad-band SED fits that constrain, for example, the conditions where the electrons are first accelerated).

The major contribution to the ultraviolet (UV) emission in the Galactic globular clusters (GGCs) comes from hottest stellar sources which includes white dwarfs, hot (OB type) post-AGB stars and BHBs. We propose to observe four GGCs, NGC 4147, NGC 1261, NGC 6229 & NGC 5033 with UVIT. These samples will provide varieties of hot UV sources to study their UV photometric properties. The comparison of UV CMDs with the stellar evolutionary tracks of low mass evolved stars will enable us to understand the evolutionary stages and classification of sources. The T_eff , log g and [Fe/H] values of UV bright stars can be derived using model atmosphere grids of such stars. The absolute UV fluxes of the sources will be useful to compare their SEDs with model atmospheres. The observed UVIT star counts will be compared with model simulation  to explore the potential for studying the structure of our Galaxy.

The major contribution to the ultraviolet (UV) emission in the Galactic globular clusters (GGCs) comes from hottest stellar sources which includes white dwarfs, hot (OB type) post-AGB stars and BHBs. We propose to observe four GGCs, NGC 4147, NGC 1261, NGC 6229 & NGC 5033 with UVIT. These samples will provide varieties of hot UV sources to study their UV photometric properties. The comparison of UV CMDs with the stellar evolutionary tracks of low mass evolved stars will enable us to understand the evolutionary stages and classification of sources. The T_eff , log g and [Fe/H] values of UV bright stars can be derived using model atmosphere grids of such stars. The absolute UV fluxes of the sources will be useful to compare their SEDs with model atmospheres. The observed UVIT star counts will be compared with model simulation  to explore the potential for studying the structure of our Galaxy.

The observed UV continuum excess in young stars provides the most direct estimate of their mass accretion rates. Such direct measurements, however, are rare because of the high line-of-sight extinction toward most young stars. Here we propose UVIT observations of 5 young accreting T Tauri stars associated with the high galactic latitude ($b \approx -34\degree$) cloud MBM 12, the extinction toward which is low. We will observe all of them in regular pointing mode in two FUV filters (BaF2 \& Sapphire) and four NUV filters (B4, B13, B15 \& N2). We will also obtain low resolution spectra of these sources with the FUV grating-2 (dispersion = 0.6 nm/arcsec) to measure the CIV line luminosity, which is known to scale with accretion luminosity. From these observations we will constrain the temperature of the accretion-shock emission and directly measure accretion rates onto these young stars.

Globular Clusters (GCs) house exotic stellar populations and are the only sites where the products of direct collision of stars (Blue Straggler stars, BSS) are found. GCs also have accreting binaries, WDs and Horizontal branch stars, which are all bright in the UV. In the UV, all these stars stand out from the swamp of the cooler main-sequence stars and red giants. Our simulations suggest that the colour-magnitude diagrams using UVIT filters create definite diagnostic regions which can be used to detect and identify these systems. Exploiting the resolution and filter system of the UVIT, we plan to derive the multi-wavelength SEDs and estimate the fundamental properties such as mass, temperature and Luminosity. NGC 5272 (M3) is one such cluster with many UV bright stars located in the cluster.

We propose to study the spectral variations in the black-hole X--ray binary 4U 1957+11 with a 20 ks observation. AstroSat has sensitivity across a broad X-ray bandwidth covered by SXT+LAXPC+CZTI and hence can probe black hole spectra over a large energy range with high time resolution capability. The main objective is to obtain the spin of 4U 1957+11 with spectroscopy, timing analysis and also investigate the variability in the hard X-rays.

Understanding the precise star-formation history of galaxies and its dependence on galaxy mass, morphology and environment is one of the most important outstanding problems in galaxy evolution. UV data, which are the most precise probe of (relatively unobscured) recent star-formation are crucial to resolving degeneracies in the modeling. For nearby galaxies of large angular size, such modeling can be carried out for individual star-forming regions. For this purpose, the unprecended angular resolution of UVIT is critically required. In this pilot study, we request UVIT observations of 5 nearby S0 galaxies, which show some evidence of recent star-formation. We will combine the UVIT UV data with archival observations in optical, near-IR and mid-IR and stellar population synthesis models to model the resolved star-formation histories of these galaxies.

Understanding the precise star-formation history of galaxies and its dependence on galaxy mass, morphology and environment is one of the most important outstanding problems in galaxy evolution. UV data, which are the most precise probe of (relatively unobscured) recent star-formation are crucial to resolving degeneracies in the modeling. For nearby galaxies of large angular size, such modeling can be carried out for individual star-forming regions. For this purpose, the unprecended angular resolution of UVIT is critically required. In this pilot study, we request UVIT observations of 5 nearby S0 galaxies, which show some evidence of recent star-formation. We will combine the UVIT UV data with archival observations in optical, near-IR and mid-IR and stellar population synthesis models to model the resolved star-formation histories of these galaxies.

$\gamma$-rays are expected to be originated in AGN jet. As emission from jet falls off rapidly with jet inclination angle, misaligned AGNs (M-AGNs) are expected to be weak $\gamma$-ray emitter. However, Fermi detected $\sim 20$ MAGNs during it's first four years of operation. Due to the large jet inclination angle, emission from M-AGNs is expected to have significant contributions from both accretion disk and AGN jet. Therefore, M-AGNs are the best laboratory to study the accretion disk-jet connection. NGC 1275 is one of the Fermi detected M-AGN which exhibits strong emission in $\gamma$-rays. To understand the radiative process in these Fermi detected M-AGNs, observations in UV and X-ray band are crucial. We propose simultaneous observation of NGC 1275 with UVIT, SXT along with LAXPC and CZTI detectors on board ASTROSAT which is essential to construct the broadband spectra of the source and to better understand the accretion disk-AGN jet connection.

Requested observation: Propose to observe GX 17+2 using LAXPC for an exposure time of 40 ks. Context: It is a Z-type neutron star source tracing out a Z track on the HID diagram. Cross-correlation function (CCF) study would be performed on GX 17+2. Since such sources vary in timescales of hours to days they are always in the verge of a state transition and hence form ideal candidates for studying connections between X-Ray state transitions and jets (Migliari et al. 2007). Objectives and Expected scientific results : Study the CCF and autocorrelation functions (ACF) of light curves in higher energy bands especially with 40-80 keV (not possible with RXTE). Study of ACFs would enable us to constrain the accretion geometry model viz. quasi spherical geometry of the corona or the extended corona geometry. We would also constrain the lags and explore the connection between them and the radio jet.

Context: 4U 1705-44 is a peculiar atoll source showing large X-ray intensity variation. The power density spectrum shows broad band noise which varies with intensity. RXTE has detected a barely visible KHz QPO at 750 Hz. During the low intensity state it shows type-I bursts and the spectrum is found to be hard. Based on Chandra data, a broad iron line (EW=1.2 keV) was reported. Objectives & Expected scientific results : Study the correlated spectral and temporal variation as it traverses on CCD and compare them with other Z sources. Study the cross-correlation functions of energy dependent light curves (i.e. 3-5 keV, 10-20 keV, 20-50 keV). We would like to explore the auto-correlation functions in various energy bands. Since LAXPC response is better than PCA/RXTE, a systematic search could confirm the presence of 750 Hz QPO .

MS 1603.6+2600 is an extraordinary eclipsing/dipping persistent neutron star low-mass X-ray binary which is unusually faint in X-rays (< 1 mCrab), and shows four types of optical variabilities, most of which are also seen in X-rays. These variabilities make this source a unique laboratory to probe accretion processes and structures (for example, the tilt, warp and precession of disk). But this probing requires simultaneous X-ray and optical data from this source over many binary orbits. Such detailed data are currently not available. Our proposed 70 ks multi-wavelength observations with AstroSat will significantly fill this lacuna, will characterize this source in an unprecedented manner, and will test the current models of variabilities. This proposal relies on the unique multi-wavelength capabilities of AstroSat.

We propose a multi wavelength observation of two high redshift luminous flat spectrum radio quasars (FSRQ), 3FGL J1656.2-3303 (z=2.4) and S5 0836+710 (z=2.172), by ASTROSAT. Both of these sources were studied using limited observations in UV, hard X-ray and Fermi-LAT. However, the synchrotron parameters could not be well constrained using such observations, as the thermal bump dominates the non-thermal low-energy emission. Combined UVIT-SXT observation can probe the thermal and the synchrotron tail of the broadband spectral energy distribution (SED) which will be useful to obtain the synchrotron/synchrotron self Compton (SSC) emission parameters of the sources. The hard X-ray region, which can be probed by LAXPC/CZTI, in the both sources interestingly shows a curvature that can probably be correlated to the minimum energy of the emitting electron distribution. Broadband observation by ASTROSAT can be combined with Fermi-LAT observation to model the complete SED and constrain the underlying model parameters.

Continuing with our ongoing campaign of studying “extreme” TeV blazars with ASTROSAT, we request observations of the “extreme” TeV blazar, 1ES 0229+200, using the multiwavelength instruments on board the ASTROSAT. We propose for 1 pointing of 40 ks which will provide unprecedented spectral resolution of the synchrotron peak and beyond of the so called class of EHBLs, which peak in the hard X-rays. Since the origin of the optical emission of these object is under debate, simultaneous UV-Xray observations using ASTROSAT can resolve this uncertainty. Study of the hard X-ray spectrum, along with TeV observations, can give us hitherto unknown clues on the extragalactic background light and also the physical processes responsible for the outbursts in blazars.

The mechanism by which disc is formed in classical Be stars is one of the open puzzles in stellar research. One of the often suggested mechanisms is the role of an ‘invisible’ hot companion in the formation of this disc. They make their presence felt in the UV and X-ray region of the electromagnetic spectrum. Our proposal is to search for the elusive Be binary systems with white-dwarf or subdwarf O-type star being the companion to Be star. Mathew et al.(2008) identified 22 and 3 Be stars in the open clusters NGC 663 and NGC 7510 respectively. The NUV magnitudes from GALEX data shows that most of these Be stars are brighter in the NUV, when compared to Be stars in other clusters which is suggestive of a hot companion. We plan to image this cluster in the FUV and NUV filters to measure, detect and characterize the UV excess.

We propose an ASTROSAT observation to study unique partial eclipse in the HMXB IGR J16393–4643 observed with Swift–BAT and Swift–XRT.From orbital intensity profile of IGR J16393–4643 constructed from long term lightcurves of Swift–BAT, we found a low intensity state, which was previously interpreted as eclipse. However, due to dissimilarities of this low intensity state from other eclipsing binaries, we propose a 100 kilosec observation of this source, with SXT, LAXPC and CZTI instrument of ASTROSAT to unveil true nature of this partial eclipse. With this observation, we also aim to carry out pulse phase resolved spectroscopy of this system, to study in detail the complex double peaked pulse profiles observed in a Suzaku observation of this source. The larger effective area of LAXPC at higher energies would also provide an excellent opportunity to study the Cyclotron Resonance Scattering Feature (CRSF) found in spectra with NuSTAR observation, in great detail.

We request 6 X-ray observations of the low mass X-ray binary, XTE J1710-281, each lasting for 12 ks with Astrosat-LAXPC. XTE J1710-281 is an eclipsing binary and has been persistently active since its discovery. The main goal of these observations will be to determine the mid eclipse times of the source and thereby study the orbital evolution in XTE J1710-281. This will enable us to better understand the probable cause for the observed orbital glitches in the source. Along with full eclipses, this source also displays thermonuclear X-ray bursts and pre-eclipse dips. In order to study the X-ray emission mechanism, we will perform the broadband spectroscopy with SXT and LAXPC during non-burst persistent, non-dip phase, as well as during the dips. We will also carry out burst spectroscopy and investigate the burst oscillation phenomena in this source.

We request 60 ks and 40 ks ASTROSAT observations of the two magnetic CVs, V2487 Oph and 1RXS J032540.0-081442 respectively to study the accretion flow characteristics on the white dwarf surface. The multi-wavelength observation will provide the information about the accretion flow geometry near the surface, the cooling mechanism of the hot accreted material. The orbital period and the white dwarf mass can also be constrained with better accuracy.

Crab the pulsar wind nebula is a potential candidate for X-ray polarimetry observations with CZTI. Pulse phase resolved polarization measurements of Crab will be helpful in constraining the pulsar emission mechanism models and geometry. We have obtained statistically significant polarization signature for Crab from the available CZTI data (~550 ks) when averaged over all phases. These observations also have provided very interesting results for polarization of pulsed emission with phase-resolved polarization analysis, which can provide insights to the pulsar emission models. However the statistical significance of these results are rather low and in order to make concrete interpretation of these results it is necessary to have much larger exposure time (~2 Ms). As the requirement of this large exposure time can not be met in a single observation cycle, we expect to achieve this over the mission life time. Hence we propose 200 ks observation of Crab in this cycle.

We propose to map the UV emission around dual nuclei in late stage galaxy mergers and interacting systems. Mergers can trigger bursts of star-formation and nuclear activity in galaxies. This can result in dual AGN and AGN+star-forming nuclei in the merging galaxies. Our targets have been observed by GALEX but not with the Hubble Space Telescope (HST) UVIS camera. The higher spatial resolution of UVIT compared to GALEX will help us resolve the dual cores and study the disk star-formation triggered by the merging process. Our targets are all low redshift, UV bright sources. We will confirm the nature of the double cores, map the associated star-formation, estimate star-formation rates and its correlation with the different types of nuclei. Not much is known about the UV emission from dual AGN/starburst nuclei; hence UVIT observations will be an important step for understanding galaxy mergers.

We propose to map the UV emission around dual nuclei in late stage galaxy mergers and interacting systems. Mergers can trigger bursts of star-formation and nuclear activity in galaxies. This can result in dual AGN and AGN+star-forming nuclei in the merging galaxies. Our targets have been observed by GALEX but not with the Hubble Space Telescope (HST) UVIS camera. The higher spatial resolution of UVIT compared to GALEX will help us resolve the dual cores and study the disk star-formation triggered by the merging process. Our targets are all low redshift, UV bright sources. We will confirm the nature of the double cores, map the associated star-formation, estimate star-formation rates and its correlation with the different types of nuclei. Not much is known about the UV emission from dual AGN/starburst nuclei; hence UVIT observations will be an important step for understanding galaxy mergers.

We propose to map the UV emission around dual nuclei in late stage galaxy mergers and interacting systems. Mergers can trigger bursts of star-formation and nuclear activity in galaxies. This can result in dual AGN and AGN+star-forming nuclei in the merging galaxies. Our targets have been observed by GALEX but not with the Hubble Space Telescope (HST) UVIS camera. The higher spatial resolution of UVIT compared to GALEX will help us resolve the dual cores and study the disk star-formation triggered by the merging process. Our targets are all low redshift, UV bright sources. We will confirm the nature of the double cores, map the associated star-formation, estimate star-formation rates and its correlation with the different types of nuclei. Not much is known about the UV emission from dual AGN/starburst nuclei; hence UVIT observations will be an important step for understanding galaxy mergers.

We propose to map the UV emission around dual nuclei in late stage galaxy mergers and interacting systems. Mergers can trigger bursts of star-formation and nuclear activity in galaxies. This can result in dual AGN and AGN+star-forming nuclei in the merging galaxies. Our targets have been observed by GALEX but not with the Hubble Space Telescope (HST) UVIS camera. The higher spatial resolution of UVIT compared to GALEX will help us resolve the dual cores and study the disk star-formation triggered by the merging process. Our targets are all low redshift, UV bright sources. We will confirm the nature of the double cores, map the associated star-formation, estimate star-formation rates and its correlation with the different types of nuclei. Not much is known about the UV emission from dual AGN/starburst nuclei; hence UVIT observations will be an important step for understanding galaxy mergers.

We propose to map the UV emission around dual nuclei in late stage galaxy mergers and interacting systems. Mergers can trigger bursts of star-formation and nuclear activity in galaxies. This can result in dual AGN and AGN+star-forming nuclei in the merging galaxies. Our targets have been observed by GALEX but not with the Hubble Space Telescope (HST) UVIS camera. The higher spatial resolution of UVIT compared to GALEX will help us resolve the dual cores and study the disk star-formation triggered by the merging process. Our targets are all low redshift, UV bright sources. We will confirm the nature of the double cores, map the associated star-formation, estimate star-formation rates and its correlation with the different types of nuclei. Not much is known about the UV emission from dual AGN/starburst nuclei; hence UVIT observations will be an important step for understanding galaxy mergers.

We propose to map the UV emission around dual nuclei in late stage galaxy mergers and interacting systems. Mergers can trigger bursts of star-formation and nuclear activity in galaxies. This can result in dual AGN and AGN+star-forming nuclei in the merging galaxies. Our targets have been observed by GALEX but not with the Hubble Space Telescope (HST) UVIS camera. The higher spatial resolution of UVIT compared to GALEX will help us resolve the dual cores and study the disk star-formation triggered by the merging process. Our targets are all low redshift, UV bright sources. We will confirm the nature of the double cores, map the associated star-formation, estimate star-formation rates and its correlation with the different types of nuclei. Not much is known about the UV emission from dual AGN/starburst nuclei; hence UVIT observations will be an important step for understanding galaxy mergers.

We propose a 100 ks observation of the outskirts of Centaurus cluster to demonstrate the capability of Astrosat for studying the faint, extended X-ray emission at the edges of galaxy clusters. The low earth orbit and small inclination of the orbital plane of Astrosat provide low and stable background, required for cluster outskirts studies. The large field of view provides sufficient grasp, enabling mapping of faint X-ray emission in the outskirts of nearby clusters. The proposed observation will allow us to measure the metallicity of the intra-cluster medium (ICM) in the outskirts of this relatively low mass cluster. Such measurements are paramount for understanding the chemical enrichment of the universe. The observation will also allow us to measure the multi-temperature structure of the gas, providing evidence for clumpy multiphase ICM in cluster outskirts, a direct probe of the ongoing virialization of the freshly accreted material from the surrounding large-scale structure.

Revealing the structure and properties of the atmosphere of exoplanets is important to understand the current state of the planets and their formation and evolution processes. The transit observation in NUV gives us information on the atmospheric properties such as composition, clouds, haze and Rayleigh scattering. The transit in FUV gives us constraints on the upper atmospheric structure. Here, we propose a 20 ks ASTROSAT observation for the hot Jupiter, WASP-31b in order to conduct transit observation in NUV and FUV. This planet is known to have a flat transmission spectrum that suggests this planet has cloudy/hazy atmosphere, and we can add new data point in the transmission spectrum of the planet by NUV transit to investigate the strong Rayleigh scattering in the atmosphere. In this proposal, we aim to investigate the transit depths in each wavelength to constrain the structures and properties of both lower and upper atmosphere.

kHz QPOs have been detected in faint low mass X-ray binaries (LMXBs) where luminosity is ~0.01 L_Edd. Also it has been observed that the amplitude of kHz QPOs increases as the luminosity goes down. We propose observations of faint LMXBs ( L_X ~0.01 L_Edd ) in which kHz QPOs have been detected at ~20 % rms. The wideband capabilities and sensitivity of Astrosat will help us understand the origin of the high amplitude oscillations. Additionally since the frequencies of the kHz QPO detected in these sources are among the highest observed, we can also probe the limits on neutron star parameters as the QPO frequency is limited by the ISCO.

Cygnus X-1, the bright black hole binary is one of the potential targets for polarimetry with CZTI. Cygnus X-1 has been extensively studied with spectral and timing observations since the early days of X-ray astronomy. In spite of these vast observations, there remains unanswered questions about the emission mechanisms. In some models hard X-ray emission is attributed solely to Compton scattering in hot corona and other models suggest contribution of Synchrotron emission from jets which are predominant in radio wavelengths. Polarization measurements in hard X-rays during different states along with the broadband spectral measurements with AstroSat will be able to constrain these different models. Cygnus X-1 has been observed by AstroSat at multiple occasions and the results from polarization analysis are promising. However in order to obtain statistically significant results, longer exposures are required. Hence we propose 200ks deep observation of Cygnus X-1.

With an unmatched combination of large effective area, high time resolution, and good spectral resolution of LAXPC, studies of stellar winds, flaring mechanism in SFXTs during outbursts and quiescense as well as their timing properties can be extensively carried out. We propose 80 ks of observation of IGR J17544-2619 during it’s brightest state in order to investigate the hard X-ray spectral properties of the source. We intend to search for pulsations, column density and spectral index variations to test the applicability of various competing models put forward for explaining SFXT behaviour. Through hardness-resolved spectral analysis in very short time-scales, we also propose to carry out deeper study of the flare triggering mechanisms.

We propose deep UVIT observations of Ursa Major-II, most dark matter dominated, ultra faint dwarf satellite galaxy of Milkyway and one of the closest objects (33kpc). It has an astrophysical J-factor higher than Reticulum-II. Reticulum-II had claims of gamma ray detections, possibly from DM annihilation. Reticulum-II was observed during A02 and the data is not available yet. Uma-II, inspite of sharing similar properties and higher J-factor, does not show evidence of DM detection. The main differences between Reticulum-II and other UDFs is the large enhancement in r-process elements. Theoretical simulations suggest that NS-NS mergers, are promising candidates for r-process production. The objective is to study stellar populations, binary fraction, metallicity distribution and morphology based on photometric metallicities, which only possible with UVIT narrow band filters, or require spectroscopy of future 30m telescopes. Search for possible diffuse UV emission as a sign of DM signature and compare with Ret-II.

Globular Clusters have largely been used to substantiate the stellar evolution models. Lately, it has been observed that globular clusters comprise multiple stellar populations that are believed to have formed in multiple star bursts spaced a several Myr apart. This is in contrast to the accepted norm where the stellar population formed in a single burst from the proto-galactic interstellar medium. We propose to observe a globular cluster in our Galaxy that has been observed in the GALEX fields and is believed to host at least 5 distinct stellar populations. We are interested in deep imaging of this globular cluster through UVIT filters to characterise the multiple stellar populations in UV.

4U 1907+09 is a highly variable source that undergoes periodic flares and aperiodic dips. We propose 80 ks of observation for 4U 1907+09 with SXT, LAXPC and CZTI onboard ASTROSAT to carry out the variability study with detailed spectral analysis. The clumpy wind around 4U 1907+09 can also be characterized from such analysis. In addition, study of the variation of cyclotron line energy with spin phase can help us understand the CRSF formation region while it’s variation with luminosity will help us understand different accretion regimes that come into play with varying luminosity. With an unmatched timing capability, we also intend to make detection of QPOs (speculated to be of ~ 18 s for 4U 1907+09) that will give us an insight into the formation of accretion disk scenario. Detailed pulse profile studies will also be carried, especially in hard X-rays to investigate X-ray beaming pattern.

We propose two observations of 30 kiloseconds of LMC X-3 separated by 50 - 70 days in order to study intensity variations in the source across different spectral bands from UV to X-rays. The source displays large variations in intensity with change of state in these variations. The variations are seen over a large wave band from infrared to X-rays with time lags present in between different bands. However, here has been no systematic study of these lags across the UV, X-ray waveband. With this proposal, we intend to study the wide-band spectrum of the binary in different states and monitor the lags in the intensity variations across the UV, X-ray wavebands using the excellent timing and spectral coverage of ASTROSAT. With this information, we hope to model the accretion geometry (wind/disk based) as a function of the precisely determined orbit of this source.

We propose three 20 ks ASTROSAT observations, each separated by 60 days of an ultra-compact neutron star X-ray binary, 4U~1820--30. It exhibits $\sim$~176 days accretion cycle. We aim at studying broadband spectrum using data from the \textsc{SXT} and \textsc{LAXPC} instruments aboard \emph{ASTROSAT} during different spectral states. This study will help us in detailed comparison of the spectral components observed during different spectral states of this source, helping in understand the disk-jet coupling mechanism. In neutron star~(NS) low mass X-ray binaries,~quasi-periodic oscillations (QPO) components observed in the frequency range of 0.01-100 Hz all correlate with one another and with that of the kilohertz QPOs. 4U 1820-30 is the first non-pulsating source which shows a frequency offset in the correlations mentioned before. LAXPC observations with much larger collecting area compared to previous X-ray mission, RXTE will be very useful to perform Rapid X-ray time Variability Study of 4U 1820-30.

AXPs and SGRs have been explained as neutron star sources with high magnetic fields (magnetars). Measurement of the magnetic fields using cyclotron line features is attempted in a very few of these sources, with the nature of the lines (ion or electron) themselves not known. The broadband and high sensitivity coverage of ASTROSAT enables a proper search for cyclotron lines in these sources. To do this, we propose an anticipated TOO observation of 5 kiloseconds of an outburst of SGR 1806-20. This source is one of the few SGRs with signatures of cyclotron lines observed during an outburst. It has the highest spin-down magnetic field and was observed in the brightest flare known among all known members of the SGR/AXP class. Thus measurement of the cyclotron parameters in this source will help understand the nature of this line and also probe the nature of the source.

The origin and evolution of hydrogen deficient stars is yet a mystery. They are presently thought to be a result of mergers of white dwarfs. In optical region the extreme helium stars (hot hydrogen deficient stars) (EHe) show very similar spectral energy distributions as normal O and B stars. Thus it is not easy to distinguish them except through high resolution spectroscopy. This limitation severely restricted the number of stars known as well as searches for them in older stellar aggregates which are very important consideration for estimating their life times and evolutionary considerations. Atmospheric models of EHe stars show that even though the optical colours are the same as normal stars the UVIT band colours are clearly different. We propose to use these indices as criteria to discover new EHes and Hydrogen deficient stars in clusters. We seek observations of two globular clusters: NGC1261 and NGC5986,in UVIT bands.

More than the 40 years after discovery, X-ray pulsar 4U~1909+07 has not yet been much explored till today. Several interesting aspects of the pulsar needed careful investigation with the instruments onboard {\it Astrosat}. We propose a $\sim$60~ks observation of 4U~1909+07 with LAXPC, CZTI, and SXT to confirm the cyclotron feature in the pulsar along with studying stellar wind dynamics of the companion. A cyclotron line at $\sim$44 keV has been tentatively detected in this pulsar which can be confirmed by using the {\it Astrosat} observation. The magnetic field geometry is also expected to be probed for the first time through phase-resolved spectroscopy. Using this observation, we will study pulse period fluctuation that indirectly constrain the magnetic field of the neutron star based on the accretion torque theory. The properties of accreting stellar wind and surrounding environment will also be investigated by using this observation.

We request 50 ks observation of the persistent X-ray binary source 1E1743.1-2843 to probe the nature of the compact star. The source has been observed for over four decades using many X-ray instruments. Although the high source luminosity indicates an accretion-driven binary, neither the nature of the compact object nor of its companion, is known. A weak soft excess and the lack of counterpart favor a neutron star in a LMXB in the low-hard state, while a hard power-law index and large nH, points towards a HMXB. With LAXPC we wish to perform a timing study and look for coherent pulsations, break frequency and thermonuclear bursts. We also wish to study the energy spectra in the 0.3-80 keV spectral band to look for cyclotron resonant scattering signatures, if any, that would help constrain the magnetic field and subsequently help resolve the ambiguity associated with the nature of this peculiar source.

We propose to observe four persistent BHCs, such as, GRS~1915+105, Cyg~X-1, LMC~X-3, 4U~1957+115 during their X-ray active phase. It would be exciting to have detailed accretion flow properties of these sources from ASTROSAT data due to its vastly enhanced capabilities as compared to the earlier instruments. Our recent study of a few BHCs from spectral fits with the two-component advective flow (TCAF) model, gave some preliminary idea about the dynamics of the mass accretion processes around a BHC. We therefore propose that we study four persistent sources to obtain their masses independently from the spectrum and timing properties as well as the variation of their mass accretion rates and other flow parameters. The origin of QPOs and their dynamic evolutions will also be studied. In order to understand variability class transitions, we propose to observe GRS~1915+105 continuously for at least two days.

We Propose for a 65 ks ASTROSAT observation of IGR J16320-4751. Source is fairly bright in X-ray (2.33 × 10-10 erg cm-2 s-1 in 2-100 kev band). It is a heavily obscured source With NH value of 2 × 1023 cm-2 found on many occasions and once rose to even higher value 5 × 1023 cm-2 . Recent studies with hydrogen column density and iron ka tracers suggest that it might be on the boundary between SG-HMXB and SFXT. With this observation we want to achieve following goals : 1) Broadband spectroscopy. 2) Study of variation of hydrogen column density. 3) Intensity and energy resolved pulse profiles. 4) Detection of cyclotron line. With ASTROSAT’s timing and spectral capabilities we will be able to detect cyclotron lines and study spectral parameter variations.

The black hole binary sources at steady low and moderate accretion rate should provide the best test case for the standard SS-disc models with accretion rate less than ten percent to few tens of percent of the Eddington limit. Nevertheless, these sources remain least studied because they show relatively less variability and are hence less spectacular in their behaviour. The purpose of this proposal is to kick start the study of these sources by observing two such black holes binary system to establish the feasibility of the study of such sources. Henceforth, more source will be added to this programme with the aim of creating a data base of canonical SS-disc model parameters observed in the Galaxy and beyond. This study will fill the void in the literature where a comparative study of the phenomenological models of fitting the data is concerned for low accretion rate, especially for hard X-rays.

The black hole binary sources at steady low and moderate accretion rate should provide the best test case for the standard SS-disc models with accretion rate less than ten percent to few tens of percent of the Eddington limit. Nevertheless, these sources remain least studied because they show relatively less variability and are hence less spectacular in their behaviour. The purpose of this proposal is to kick start the study of these sources by observing two such black holes binary system to establish the feasibility of the study of such sources. Henceforth, more source will be added to this programme with the aim of creating a data base of canonical SS-disc model parameters observed in the Galaxy and beyond. This study will fill the void in the literature where a comparative study of the phenomenological models of fitting the data is concerned for low accretion rate, especially for hard X-rays.

We propose to measure time-lag, as a function of wavelength, between the optical/UV and X-rays and verify if the NGC5273 hosts standard disks. AstroSat's capability of simultaneous observations in multiple optical/UV bands and X-rays is uniquely suited for this technique. Recent Swift monitoring of five AGN have resulted in the best ever measurement of AGN X-ray/UV/optical inter-band lags, showing that optical/UV short timescale variability is mostly due to reprocessing of X-rays by an accretion disc. However the lags are ~3 times longer than expected from a standard disc. There seems to be some issue with our understanding of accretion discs. To further investigate, it is important to measure the lag-wavelength relation in AGN with different properties. NGC5273, with mass 8 times less than NC5548 and approved XMM-Newton observation is well suited for multi-wavelength observations. Hence, we request 30 ks AstroSat observation, with UVIT as the primary instrument, of NGC~5273.

After exhibiting successive Type-I outbursts over a period of 27 years, the Be X-ray binary EXO 2030+375 went through a quiescent period spanning about 4-5 orbital cycles. It has very recently returned to it’s previous ‘normal’ state when it exhibit outbursts. With the proposed observation we would like to probe if the accretion mode is same as before by studying (i) the pulse profile over a wide energy band (ii) the broad band X-ray spectrum before and after the period of predicted outburst. To achieve this, we propose two 40 ks of observation of EXO 2030+375 during and after the peak of the outburst, the timing of which is predictable. We will investigate if the accretion and/or emission characteristics of the source has changed during the renewed activity after the quiescence of several orbital cycles Broad-band spectral as well as timing properties will be studied with LAXPC, SXT and CZTI.

MWA (Murchison Wide Field Array) radio observations at 200 MHz reveal diffuse radio emission from relics situated at the edge of A3223 and A761 clusters. In low resolution X-ray images, the two clusters seem to be elongated and non-relaxed. Presently, no high quality X-ray data is available to study their morphologies and X-ray properties in detail. Here we are proposing 50 ks observation of each cluster with Astrosat SXT. The observations will allow us to study spatial variations of spectral properties of these clusters. Simultaneous observations with LAXPC will be used to detect any hard X-ray non-thermal emission associated with merger shocks.

Supersoft X-ray sources (SSS) are highly luminous low-kT X-ray sources, interpreted as a accreting white dwarf at a very high rate, leading to Eddington-limited, steady H-burning on the WD surface at T~15-80 eV. Reprocessing of this emission in the disc and companion leads to high optical/UV fluxes. Maintaining the high ${\dot{M}}_{\odot}$ requires either a high mass donor (for $P_{orb}>6$hrs) or extreme irradiation of a low-mass donor to drive a wind ($<$6hrs). There are two eclipsing SSS in the Magellanic Clouds: 1E0035.4-7230, also known as 2E0035.4-7229 (SMC, P=4.1h), CAL87 (LMC, P=10.6h) for which ASTROSAT is ideal for obtaining simultanoeus full-cycle orbital light-curves in the UV/soft X-rays for the first time, so as to model the disc, disc-wind and SSS components. This has the potential to resolve the controversy over whether the mass-ratio is inverted (high-mass donors) or similar to CVs (low-mass donors), and is important given their candidacy as SNIa progenitors.

We propose a 60 ks observation of the high mass X-ray binary 4U~1700-37 with {\it Astrosat} during late orbit and eclipse phases of the binary. The nature of compact object is still unclear in the system, although the source is identified as a neutron star based on the spectral shape and tentative detection of the cyclotron absorption line at $\sim$39 keV. The presence/ absence of cyclotron line can be tested with high sensitivity instruments onboard {\it Astrosat}. Furthermore, the causes of rapid spectral variability or flares like episodes on long and short time scales will be explored in detail. It would be interesting to investigate the pulsation in the iron line as well as exploring the source properties at different orbital phases. A signature of accretion wake is also expected to trace at late orbital phases predicated from optical observations.

The massive binary systems with strong stellar winds play a crucial role in the stellar evolution as well as the galactic evolution. The existence of strong winds and the interaction of the winds from both the massive stars are considered to be the primary reason of the high energy emission (from X-rays to gamma-rays) from this class of objects. But physical mechanisms of the generation of high energy emission from such systems are still under debate, as the nature of the high energy emission from massive binaries is not clear. The X-ray spectra for massive binaries are usually dominated by the thermal emission within energy range 0.2 - 12.0 keV. The nature of the hard X-ray is unknown. The binary phase resolved observation is necessary to determine the physical connection between the X-ray and gamma-ray emissions along with the emission in optical and radio range.

We request 80 ks {\it AstroSat} observations of NGC~4748, a narrow line Seyfert 1 galaxy and one of the lowest black hole mass active galactic nucleus. This AGN exhibits strong and rapid variations in the UV/optical and X-ray bands. These variations have never been studied in detail to date in this AGN . The available observation shows dips and declining trend present in the UV and the X-ray bands. These features in the UV bands appear to be delayed on lightcrossing timescale with respect to the X-ray bands. Due to the lack of long UV/optical and X-ray observation, we propose long observation to study these variations using unprecedented multi-wavelength capability UVIT, SXT, LAXPC and CZTI instruments onboard {\it AstroSat}. The main aim of this proposal is to study the correlation between the UV/optical and the X-ray bands, and to derive the lag spectrum to study the nature of accretion disk.

We propose to undertake deep ultra-violet (FUV+NUV) imaging (~10ks) of two gas-rich dwarf galaxies recently discovered in the local universe. These systems straddle a star-formation threshold: one is actively forming stars and the other appears to have recently ceased star formation. Both contain significant reservoirs of gas but have surprisingly weak star formation. In addition to our extensive multi-wavelength followup observations, deep high-resolution UV images are essential to complete our understanding of the unusual star formation processes underway in these extremely metal-poor gas-rich dwarf galaxies.

The massive binary systems with strong stellar winds play an important role in the stellar as well as the galactic evolution. The interaction of stellar winds from both the massive stars are thought to be responsible for high energy (X-ray to gamma-ray) and radio emission. The physical processes responsible for the multiwavelength emission from massive binaries are still under investigation. We propose to observe WR 125, which is thermal and non-thermal radio, X-ray emitter as well as shows episodic dust formation. The proposed multi epoch observations of this extremely long period binary (>6600 days) would help us to gain a deeper insight into the dynamics of stellar winds. The high quality X-ray data from astrosat would also provide a strong test of the latest theoretical models that aim to explain the emission from massive binaries over the whole electromagnetic spectrum.

We propose a 30 ks observation with Astrosat of the bright neutron-star LMXB 4U 0614+091. Our aims are (1) to detect and follow the properties of kHz QPOs, with particular emphasis on the distribution of frequencies; (2) to study the low-frequency variability (noise and QPO) and compare it with that of other neutron-star and black-hole systems; (3) to search for oscillations during X-ray bursts to confirm the detection of the neutron-star spin period; (4) to study the energy spectrum and its variations, testing competing models for the broad-band spectral distributions. We will make use of the data from the three X-ray instruments and ask for UVIT to be switched off.

The neutron star SAX J1808.4-3658 (hereafter J1808) was the first discovered accreting millisecond period X-ray pulsar (AMXP). J1808 is a "Rosetta Stone" system showing the evolutionary role of accretion in spinning neutron stars up to millisecond (ms) spin periods in low mass X-ray binaries (LMXBs) to form ms radio pulsars. The observed X-ray pulsations originate from the neutron star''''''''s surface, allowing pulse-shape analyses to determine the star''''''''s mass and radius, which could allow the equation of state of ultra-dense nuclear matter to be constrained. The pulsations are only visible when the AMXP is in a bright state (outburst). We propose to observe J1808 for 40ks during its next outburst, allowing us to measure its spectrum and pulse shapes. These will be used to determine the neutron star''''''''s mass, radius, and orbital period changes, leading to better understanding of the properties of neutron stars and accretion in LMXBs.

M31 is the nearest giant spiral galaxy for which we can study the supernova remnants, X-ray sources, and stellar populations. At a distance of 780 kpc, M31 is far enough away that the brightest stars are safe to observe with UVIT, yet close enough to obtain a good census of the supernova remnants, X-ray sources, and hot stellar populations. The high spatial resolution of UVIT will yield outstanding data on the stellar populations of M31. The spatial resolution of SXT is sufficient to resolve the X-ray source populations which includes measuring the supernova remnant population. The resulting multi-wavelength images of M31 will form a legacy dataset to be used for study of the stellar populations of M31, it star formation history and the structure of the galaxy.

M31 is the nearest giant spiral galaxy for which we can study the supernova remnants, X-ray sources, and stellar populations. At a distance of 780 kpc, M31 is far enough away that the brightest stars are safe to observe with UVIT, yet close enough to obtain a good census of the supernova remnants, X-ray sources, and hot stellar populations. The high spatial resolution of UVIT will yield outstanding data on the stellar populations of M31. The spatial resolution of SXT is sufficient to resolve the X-ray source populations which includes measuring the supernova remnant population. The resulting multi-wavelength images of M31 will form a legacy dataset to be used for study of the stellar populations of M31, it star formation history and the structure of the galaxy.

M31 is the nearest giant spiral galaxy for which we can study the supernova remnants, X-ray sources, and stellar populations. At a distance of 780 kpc, M31 is far enough away that the brightest stars are safe to observe with UVIT, yet close enough to obtain a good census of the supernova remnants, X-ray sources, and hot stellar populations. The high spatial resolution of UVIT will yield outstanding data on the stellar populations of M31. The spatial resolution of SXT is sufficient to resolve the X-ray source populations which includes measuring the supernova remnant population. The resulting multi-wavelength images of M31 will form a legacy dataset to be used for study of the stellar populations of M31, it star formation history and the structure of the galaxy.

M31 is the nearest giant spiral galaxy for which we can study the supernova remnants, X-ray sources, and stellar populations. At a distance of 780 kpc, M31 is far enough away that the brightest stars are safe to observe with UVIT, yet close enough to obtain a good census of the supernova remnants, X-ray sources, and hot stellar populations. The high spatial resolution of UVIT will yield outstanding data on the stellar populations of M31. The spatial resolution of SXT is sufficient to resolve the X-ray source populations which includes measuring the supernova remnant population. The resulting multi-wavelength images of M31 will form a legacy dataset to be used for study of the stellar populations of M31, it star formation history and the structure of the galaxy.

M31 is the nearest giant spiral galaxy for which we can study the supernova remnants, X-ray sources, and stellar populations. At a distance of 780 kpc, M31 is far enough away that the brightest stars are safe to observe with UVIT, yet close enough to obtain a good census of the supernova remnants, X-ray sources, and hot stellar populations. The high spatial resolution of UVIT will yield outstanding data on the stellar populations of M31. The spatial resolution of SXT is sufficient to resolve the X-ray source populations which includes measuring the supernova remnant population. The resulting multi-wavelength images of M31 will form a legacy dataset to be used for study of the stellar populations of M31, it star formation history and the structure of the galaxy.

M31 is the nearest giant spiral galaxy for which we can study the supernova remnants, X-ray sources, and stellar populations. At a distance of 780 kpc, M31 is far enough away that the brightest stars are safe to observe with UVIT, yet close enough to obtain a good census of the supernova remnants, X-ray sources, and hot stellar populations. The high spatial resolution of UVIT will yield outstanding data on the stellar populations of M31. The spatial resolution of SXT is sufficient to resolve the X-ray source populations which includes measuring the supernova remnant population. The resulting multi-wavelength images of M31 will form a legacy dataset to be used for study of the stellar populations of M31, it star formation history and the structure of the galaxy. For this proposal we are requesting fields 8 to 13 of the 19 fields required for the full M31 survey.

M31 is the nearest giant spiral galaxy for which we can study the supernova remnants, X-ray sources, and stellar populations. At a distance of 780 kpc, M31 is far enough away that the brightest stars are safe to observe with UVIT, yet close enough to obtain a good census of the supernova remnants, X-ray sources, and hot stellar populations. The high spatial resolution of UVIT will yield outstanding data on the stellar populations of M31. The spatial resolution of SXT is sufficient to resolve the X-ray source populations which includes measuring the supernova remnant population. The resulting multi-wavelength images of M31 will form a legacy dataset to be used for study of the stellar populations of M31, it star formation history and the structure of the galaxy. For this proposal we are requesting fields 8 to 13 of the 19 fields required for the full M31 survey.

M31 is the nearest giant spiral galaxy for which we can study the supernova remnants, X-ray sources, and stellar populations. At a distance of 780 kpc, M31 is far enough away that the brightest stars are safe to observe with UVIT, yet close enough to obtain a good census of the supernova remnants, X-ray sources, and hot stellar populations. The high spatial resolution of UVIT will yield outstanding data on the stellar populations of M31. The spatial resolution of SXT is sufficient to resolve the X-ray source populations which includes measuring the supernova remnant population. The resulting multi-wavelength images of M31 will form a legacy dataset to be used for study of the stellar populations of M31, it star formation history and the structure of the galaxy. For this proposal we are requesting fields 8 to 13 of the 19 fields required for the full M31 survey.

M31 is the nearest giant spiral galaxy for which we can study the supernova remnants, X-ray sources, and stellar populations. At a distance of 780 kpc, M31 is far enough away that the brightest stars are safe to observe with UVIT, yet close enough to obtain a good census of the supernova remnants, X-ray sources, and hot stellar populations. The high spatial resolution of UVIT will yield outstanding data on the stellar populations of M31. The spatial resolution of SXT is sufficient to resolve the X-ray source populations which includes measuring the supernova remnant population. The resulting multi-wavelength images of M31 will form a legacy dataset to be used for study of the stellar populations of M31, it star formation history and the structure of the galaxy. For this proposal we are requesting fields 8 to 13 of the 19 fields required for the full M31 survey.

M31 is the nearest giant spiral galaxy for which we can study the supernova remnants, X-ray sources, and stellar populations. At a distance of 780 kpc, M31 is far enough away that the brightest stars are safe to observe with UVIT, yet close enough to obtain a good census of the supernova remnants, X-ray sources, and hot stellar populations. The high spatial resolution of UVIT will yield outstanding data on the stellar populations of M31. The spatial resolution of SXT is sufficient to resolve the X-ray source populations which includes measuring the supernova remnant population. The resulting multi-wavelength images of M31 will form a legacy dataset to be used for study of the stellar populations of M31, it star formation history and the structure of the galaxy. For this proposal we are requesting fields 8 to 13 of the 19 fields required for the full M31 survey.

M31 is the nearest giant spiral galaxy for which we can study the supernova remnants, X-ray sources, and stellar populations. At a distance of 780 kpc, M31 is far enough away that the brightest stars are safe to observe with UVIT, yet close enough to obtain a good census of the supernova remnants, X-ray sources, and hot stellar populations. The high spatial resolution of UVIT will yield outstanding data on the stellar populations of M31. The spatial resolution of SXT is sufficient to resolve the X-ray source populations which includes measuring the supernova remnant population. The resulting multi-wavelength images of M31 will form a legacy dataset to be used for study of the stellar populations of M31, it star formation history and the structure of the galaxy. For this proposal we are requesting fields 8 to 13 of the 19 fields required for the full M31 survey.

In our ongoing eforts to understand galaxy evolution by infall merger and AGN feedback, we propose here Astrosat UVIT observation of IC3418 and NGC3801, two best possible targets for high resolution study. IC3418 is the nearest Jellyfish of Fireball galaxy where ram pressure triggers star formation in the stripped gas tail. Our Subaru spectroscopy and stellar population study using GALEX give puzzling results which require higher resolution Astrosat observation. This is a potential Rosetta Stone for star formation study. We wish to apply this on Cosmic leafblower galaxy NGC3801. We found NGC3801 to be a post-merger early-type galaxy where first episode of thermal wind has already blown away the ISM leaving the host optically red and second non-thermal jet is about to hit the outer star forming region in just 10 million years. This AGN-feedback caught-in-the-act is the nearest such case and best oppertunity to study positive and negative feedback.

In our ongoing eforts to understand galaxy evolution by infall merger and AGN feedback, we propose here Astrosat UVIT observation of IC3418 and NGC3801, two best possible targets for high resolution study. IC3418 is the nearest Jellyfish of Fireball galaxy where ram pressure triggers star formation in the stripped gas tail. Our Subaru spectroscopy and stellar population study using GALEX give puzzling results which require higher resolution Astrosat observation. This is a potential Rosetta Stone for star formation study. We wish to apply this on Cosmic leafblower galaxy NGC3801. We found NGC3801 to be a post-merger early-type galaxy where first episode of thermal wind has already blown away the ISM leaving the host optically red and second non-thermal jet is about to hit the outer star forming region in just 10 million years. This AGN-feedback caught-in-the-act is the nearest such case and best oppertunity to study positive and negative feedback.

We propose to make observation of a transient Be/X-ray pulsar with Astrosat during an outburst. We have chosen eight objects which have shown frequent Type-I and Type-II outbursts. Cyclotron Resonance Scattering Features (CRSFs) are observed as absorption-like lines in the spectra of some of the accreting X-ray pulsars. The detection of CRSFs in the spectra of accreting pulsars is the only direct way for the measurement of the magnetic field strength near to the surface of the neutron star. CRSFs is known in a few of these sources. We will search for QPOs in these sources. The QPOs, if produced due to the inhomogeneity in the inner accretion disk, along with broad band X-ray luminosity, also allows the estimation of the magnetic field. Comparison of the above two will allow us to test applicability of the theory of accretion onto highly magnetized neutron stars.

We propose to make observation of a transient Be/X-ray pulsar with Astrosat during an outburst. We have chosen eight objects which have shown frequent Type-I and Type-II outbursts. Cyclotron Resonance Scattering Features (CRSFs) are observed as absorption-like lines in the spectra of some of the accreting X-ray pulsars. The detection of CRSFs in the spectra of accreting pulsars is the only direct way for the measurement of the magnetic field strength near to the surface of the neutron star. CRSFs is known in a few of these sources. We will search for QPOs in these sources. The QPOs, if produced due to the inhomogeneity in the inner accretion disk, along with broad band X-ray luminosity, also allows the estimation of the magnetic field. Comparison of the above two will allow us to test applicability of the theory of accretion onto highly magnetized neutron stars.

We propose to make observation of a transient Be/X-ray pulsar with Astrosat during an outburst. We have chosen eight objects which have shown frequent Type-I and Type-II outbursts. Cyclotron Resonance Scattering Features (CRSFs) are observed as absorption-like lines in the spectra of some of the accreting X-ray pulsars. The detection of CRSFs in the spectra of accreting pulsars is the only direct way for the measurement of the magnetic field strength near to the surface of the neutron star. CRSFs is known in a few of these sources. We will search for QPOs in these sources. The QPOs, if produced due to the inhomogeneity in the inner accretion disk, along with broad band X-ray luminosity, also allows the estimation of the magnetic field. Comparison of the above two will allow us to test applicability of the theory of accretion onto highly magnetized neutron stars.

We propose to make observation of a transient Be/X-ray pulsar with Astrosat during an outburst. We have chosen eight objects which have shown frequent Type-I and Type-II outbursts. Cyclotron Resonance Scattering Features (CRSFs) are observed as absorption-like lines in the spectra of some of the accreting X-ray pulsars. The detection of CRSFs in the spectra of accreting pulsars is the only direct way for the measurement of the magnetic field strength near to the surface of the neutron star. CRSFs is known in a few of these sources. We will search for QPOs in these sources. The QPOs, if produced due to the inhomogeneity in the inner accretion disk, along with broad band X-ray luminosity, also allows the estimation of the magnetic field. Comparison of the above two will allow us to test applicability of the theory of accretion onto highly magnetized neutron stars.

We propose to make observation of a transient Be/X-ray pulsar with Astrosat during an outburst. We have chosen eight objects which have shown frequent Type-I and Type-II outbursts. Cyclotron Resonance Scattering Features (CRSFs) are observed as absorption-like lines in the spectra of some of the accreting X-ray pulsars. The detection of CRSFs in the spectra of accreting pulsars is the only direct way for the measurement of the magnetic field strength near to the surface of the neutron star. CRSFs is known in a few of these sources. We will search for QPOs in these sources. The QPOs, if produced due to the inhomogeneity in the inner accretion disk, along with broad band X-ray luminosity, also allows the estimation of the magnetic field. Comparison of the above two will allow us to test applicability of the theory of accretion onto highly magnetized neutron stars.

We propose to make observation of a transient Be/X-ray pulsar with Astrosat during an outburst. We have chosen eight objects which have shown frequent Type-I and Type-II outbursts. Cyclotron Resonance Scattering Features (CRSFs) are observed as absorption-like lines in the spectra of some of the accreting X-ray pulsars. The detection of CRSFs in the spectra of accreting pulsars is the only direct way for the measurement of the magnetic field strength near to the surface of the neutron star. CRSFs is known in a few of these sources. We will search for QPOs in these sources. The QPOs, if produced due to the inhomogeneity in the inner accretion disk, along with broad band X-ray luminosity, also allows the estimation of the magnetic field. Comparison of the above two will allow us to test applicability of the theory of accretion onto highly magnetized neutron stars.

We propose to make observation of a transient Be/X-ray pulsar with Astrosat during an outburst. We have chosen eight objects which have shown frequent Type-I and Type-II outbursts. Cyclotron Resonance Scattering Features (CRSFs) are observed as absorption-like lines in the spectra of some of the accreting X-ray pulsars. The detection of CRSFs in the spectra of accreting pulsars is the only direct way for the measurement of the magnetic field strength near to the surface of the neutron star. CRSFs is known in a few of these sources. We will search for QPOs in these sources. The QPOs, if produced due to the inhomogeneity in the inner accretion disk, along with broad band X-ray luminosity, also allows the estimation of the magnetic field. Comparison of the above two will allow us to test applicability of the theory of accretion onto highly magnetized neutron stars.

We propose to make observation of a transient Be/X-ray pulsar with Astrosat during an outburst. We have chosen eight objects which have shown frequent Type-I and Type-II outbursts. Cyclotron Resonance Scattering Features (CRSFs) are observed as absorption-like lines in the spectra of some of the accreting X-ray pulsars. The detection of CRSFs in the spectra of accreting pulsars is the only direct way for the measurement of the magnetic field strength near to the surface of the neutron star. CRSFs is known in a few of these sources. We will search for QPOs in these sources. The QPOs, if produced due to the inhomogeneity in the inner accretion disk, along with broad band X-ray luminosity, also allows the estimation of the magnetic field. Comparison of the above two will allow us to test applicability of the theory of accretion onto highly magnetized neutron stars.

We propose to make observation of a transient Be/X-ray pulsar with Astrosat during an outburst. We have chosen eight objects which have shown frequent Type-I and Type-II outbursts. Cyclotron Resonance Scattering Features (CRSFs) are observed as absorption-like lines in the spectra of some of the accreting X-ray pulsars. The detection of CRSFs in the spectra of accreting pulsars is the only direct way for the measurement of the magnetic field strength near to the surface of the neutron star. CRSFs is known in a few of these sources. We will search for QPOs in these sources. The QPOs, if produced due to the inhomogeneity in the inner accretion disk, along with broad band X-ray luminosity, also allows the estimation of the magnetic field. Comparison of the above two will allow us to test applicability of the theory of accretion onto highly magnetized neutron stars.

A new class of non-shell burning symbiotic stars have recently been proposed without any emission lines in their optical spectra thereby making their detection difficult. Here we propose UVIT observations of five such potential objects from AGB branch. These objects have shown excess of UV fluxes in the photometry and are promising candidates of potential symbiotic systems. We propose multi band UVIT pointing observations to reconstruct their spectral energy distribution (SED) in UV as well as long duration observations to record flickering in selective filters. The possible correlation between flickering and expected symbiotic nature would be helpful in establishing flickering as a tool for the search of this class of new symbiotics. Total UVIT integration time of 96 ksecs (17 to 22 ksecs per source) is proposed, optimised for required SNR in different filters. SXT is requested to be secondary instrument for a plausible UV-X-ray correlation studies.

A new class of non-shell burning symbiotic stars have recently been proposed without any emission lines in their optical spectra thereby making their detection difficult. Here we propose UVIT observations of five such potential objects from AGB branch. These objects have shown excess of UV fluxes in the photometry and are promising candidates of potential symbiotic systems. We propose multi band UVIT pointing observations to reconstruct their spectral energy distribution (SED) in UV as well as long duration observations to record flickering in selective filters. The possible correlation between flickering and expected symbiotic nature would be helpful in establishing flickering as a tool for the search of this class of new symbiotics. Total UVIT integration time of 96 ksecs (17 to 22 ksecs per source) is proposed, optimised for required SNR in different filters. SXT is requested to be secondary instrument for a plausible UV-X-ray correlation studies.

In a detailed study of dwarf galaxies in nearby clusters, we have found that most of them show evidence, from a number of sources, for the presence of young stellar populations. Here we propose to characterise this young stellar population in the much more sensitive ultraviolet regime, to study its age, mass and radial extent. This will provide us with crucial information of how dwarf galaxies in clusters are still being built up at present time, and how they were able to retain their gas. We propose to obtain high spetial resolution UVIT images of 3 fields in the nearby Fornax cluster, with different environmental characteristics, for which we have a large amount of complementary data. This study will give information about the effectiveness of galaxies in holding onto some of their interstellar matter and converting it into stars, despite being subject to the intracluster radiation field.

In a detailed study of dwarf galaxies in nearby clusters, we have found that most of them show evidence, from a number of sources, for the presence of young stellar populations. Here we propose to characterise this young stellar population in the much more sensitive ultraviolet regime, to study its age, mass and radial extent. This will provide us with crucial information of how dwarf galaxies in clusters are still being built up at present time, and how they were able to retain their gas. We propose to obtain high spetial resolution UVIT images of 3 fields in the nearby Fornax cluster, with different environmental characteristics, for which we have a large amount of complementary data. This study will give information about the effectiveness of galaxies in holding onto some of their interstellar matter and converting it into stars, despite being subject to the intracluster radiation field.

In a detailed study of dwarf galaxies in nearby clusters, we have found that most of them show evidence, from a number of sources, for the presence of young stellar populations. Here we propose to characterise this young stellar population in the much more sensitive ultraviolet regime, to study its age, mass and radial extent. This will provide us with crucial information of how dwarf galaxies in clusters are still being built up at present time, and how they were able to retain their gas. We propose to obtain high spetial resolution UVIT images of 3 fields in the nearby Fornax cluster, with different environmental characteristics, for which we have a large amount of complementary data. This study will give information about the effectiveness of galaxies in holding onto some of their interstellar matter and converting it into stars, despite being subject to the intracluster radiation field.

The multiple stellar populations in Globular Clusters, discovered in recent times, is observed to be widespread, and has implications for the formation of the Milky Way. The dearth of globular clusters with single population stars, i.e. only the first generation (FG) stars is attributed to factors such as cluster expansion due to primordial gas expulsion, mass loss of SNII ejecta or accretion history of Milky Way. Through this proposal, we plan to investigate two FG rich globular clusters: E3 and NGC 5024 for their UV characterisation. The former is believed to be comprised of a single stellar population while the latter has significantly large population of FG stars. This study will enhance and diversify our investigation of globular clusters with UVIT as the two globular clusters proposed by us in the previous cycles have multiple populations and are therefore dominated by the second generation stars.

We request 10*10ks observations of GRS~1915+105 simultaneously with our Swift-INTEGRAL-NICER observations. GRS~1915+105 is a superb laboratory to study accretion/ejection. It does in short time what other sources do over day/week timescales. It is easy to catch its multi-wavelengths variations and study their origin and (co-)relations with broad band monitorings. We have obtained time with INTEGRAL, Swift, the Sardinian and Medicina radio telescope (radio), and have access to NICER. We aim to -study the origin of the high variability of GRS~1915+105 in the 0.5-40 keV -probe the physics of accretion with 0.5-1000 keV spectroscopic analysis -understand the connections between accretion and ejection processes -constrain physical models of emission processes. All these aspects can be covered by looking into the interplay between the soft and hard X-ray emitters (Astrosat, NICER, Swift/XRT, INTEGRAL), with (quasi-)simultaneous broad band coverages, and above all study of the fast temporal variability (Astrosat, NICER).

We propose to observe the UV emission from the outer stellar disk of the late type spiral galaxy NGC6946 which is one of the few galaxies that shows signatures of HI gas accretion onto its disk. It is an isolated, star forming galaxy located in the nearby Local Void. Star formation has been detected in its outer disk from Halpha emission. We will use UV observations to investigate the nature of the outer disk star formation, estimate its rate and see if it is related to the gas accretion. The high sensitivity of UVIT will allow us to image the UV disk, isolate the star forming knots and see how it correlates with the Halpha and HI emission. We will compare star formation in two different environments - the high density inner disk and halo dominated outer disk, as well as determine if gas accretion triggers the star formation.

Due to the presence of Compton thick absorber along the line-of-sight in Seyfert 2 galaxies, the soft X-ray emission, and the hard X-ray variability is significantly reduced. However, NGC 2110 is an exception. Despite being an obscured broad line region (BLR) Seyfert galaxy with a moderately thick, multi-component, complex absorber, NGC 2110 show strong hard X-ray variability and soft X-ray emission below 2 keV. Two broadband Suzaku spectra showed the presence of complex absorber with a hint of absorption induced variability. We propose broadband monitoring of NGC 2110 using three 20 ks exposures each with a gap of one year. Being very bright and variable, such monitoring of NGC 2110 would provide a unique opportunity to probe the nature and timescale of the absorption induced variability of the complex absorber, hard X-ray emitting coronal properties and the nature of soft X-ray emission over a year timescale.

We request five SXT + LAXPC observations of Cen A, spaced 45--60 days apart. Cen A, the nearest radio-loud AGN, is currently in a historically near-low X-ray flux state; accurate measurements of the photon index during this low state can yield new SED model constraints on the jet emission mechanism. We will also monitor variable line of sight column density to probe the physical structure of the circumnuclear X-ray-absorbing gas, which contains both a clumpy/cloudy component and a mildly-inhomogeneous torus. We will search for new eclipse events due to clouds transiting the line of sight to the central X-ray source; if one occurs, we will request a ToO for more dense monitoring to constrain the cloud''''''''s transverse density profile.

Our goal is to investigate the physics of relativistic jets launched by accreting supermassive black holes (i.e., AGN) within the framework of the "Blazar Divide". We propose monitoring the chromaticity of the variability of three prioritized LAXPC-bright, UVIT-safe AGN, mildly time-constrained (~30±10day cadence) using the full multi-wavelength capability of ASTROSAT. LAXPC is listed as the primary instrument because it drives the requested exposures. Therefore SXT and UVIT detection is guaranteed but a non-detecton by the LAXPC does not significantly impact our science. We will harness the Whole Earth Blazar Telescope for quasi-simultaneous ground-based observations, covering optical/IR/radio photometry, optical/radio (uGMRT) polarimetry and optical spectroscopy, and also add co-epochal Fermi data. The AGN span a range of power, nuclear-to-host-galaxy ratio and inverse-Compton dominance. We request 47ksecs/epoch each (~4 AO4 epochs) with LAXPC, SXT, CZTI and UVIT, totalling 188ksecs. We do not expect CZTI detections, but the data will inform our future proposals.

We propose to observe the UV emission from the low luminosity stellar disks of seven spiral galaxies that have extended ultraviolet (XUV) disks. Our targets have all been detected by GALEX. They are all nearby spirals that we have selected based on their UV luminosity. XUV galaxies show star formation well beyond their optical disks, in regions where the disk surface density lies below the threshold for star formation. GALEX found that 30% of spiral galaxies have XUV disks. The star formation is thought to be triggered by gas accretion from nearby clouds, galaxies or the intergalactic medium. In this study we will investigate the nature of XUV disk star formation, estimate its rate and morphology. The high sensitivity of UVIT will help isolate the star forming knots, image the UV disks and search for signatures of gas accretion. This is a continuation of a pilot study from earlier cycles.

We propose to observe the UV emission from the low luminosity stellar disks of seven spiral galaxies that have extended ultraviolet (XUV) disks. Our targets have all been detected by GALEX. They are all nearby spirals that we have selected based on their UV luminosity. XUV galaxies show star formation well beyond their optical disks, in regions where the disk surface density lies below the threshold for star formation. GALEX found that 30% of spiral galaxies have XUV disks. The star formation is thought to be triggered by gas accretion from nearby clouds, galaxies or the intergalactic medium. In this study we will investigate the nature of XUV disk star formation, estimate its rate and morphology. The high sensitivity of UVIT will help isolate the star forming knots, image the UV disks and search for signatures of gas accretion. This is a continuation of a pilot study from earlier cycles.

We propose to observe the UV emission from the low luminosity stellar disks of seven spiral galaxies that have extended ultraviolet (XUV) disks. Our targets have all been detected by GALEX. They are all nearby spirals that we have selected based on their UV luminosity. XUV galaxies show star formation well beyond their optical disks, in regions where the disk surface density lies below the threshold for star formation. GALEX found that 30% of spiral galaxies have XUV disks. The star formation is thought to be triggered by gas accretion from nearby clouds, galaxies or the intergalactic medium. In this study we will investigate the nature of XUV disk star formation, estimate its rate and morphology. The high sensitivity of UVIT will help isolate the star forming knots, image the UV disks and search for signatures of gas accretion. This is a continuation of a pilot study from earlier cycles.

We propose to observe the UV emission from the low luminosity stellar disks of seven spiral galaxies that have extended ultraviolet (XUV) disks. Our targets have all been detected by GALEX. They are all nearby spirals that we have selected based on their UV luminosity. XUV galaxies show star formation well beyond their optical disks, in regions where the disk surface density lies below the threshold for star formation. GALEX found that 30% of spiral galaxies have XUV disks. The star formation is thought to be triggered by gas accretion from nearby clouds, galaxies or the intergalactic medium. In this study we will investigate the nature of XUV disk star formation, estimate its rate and morphology. The high sensitivity of UVIT will help isolate the star forming knots, image the UV disks and search for signatures of gas accretion. This is a continuation of a pilot study from earlier cycles.

We propose to study UV extinction and dust properties in different Galactic environments. In A04 cycle we propose to observe hot stars (i) HD 29647 in the Taurus dark cloud, known for anomalous UV extinction (ii) BD+30 540 and BD+30 549 in reflection nebula NGC 1333 inside a dark cloud L1450. (iii) HD12746 in a cloud complex at high Galactic lattitude $b > 70^{\circ}$. We plan deep imaging in multiple FUV and NUV bands of UVIT to study variation in the UV extinction properties at different environments of Galaxy. NUV-B15 filter will be used to measure the strength of $2200~\AA~$ UV bump.

Fast-timing X-ray features, such as kilohertz quasi-periodic oscillations (kHz QPOs) and thermonuclear burst brightness oscillations, of neutron star low-mass X-ray binaries (LMXBs) are ideal tools to probe the fundamental physics of dense matter and strong gravity. However, so far these features could not be studied in a broad energy band extending below 2 keV. This can now be done with NICER and AstroSat/LAXPC, which together are the largest X-ray instruments ever in the 0.3-80 keV band, and currently the only instruments with fast X-ray timing capability. Therefore, we propose for a total 100 ks of joint observations with NICER and AstroSat of two neutron star LMXBs, 4U 1636-536 and 4U 1820-30. These observations will provide new knowledge about kHz QPOs and burst oscillations, thus making a significant progress in understanding the fundamental physics of neutron stars. Besides, these observations will enable a unique fast-timing cross-calibration between two X-ray instruments.

Fast-timing X-ray features, such as kilohertz quasi-periodic oscillations (kHz QPOs) and thermonuclear burst brightness oscillations, of neutron star low-mass X-ray binaries (LMXBs) are ideal tools to probe the fundamental physics of dense matter and strong gravity. However, so far these features could not be studied in a broad energy band extending below 2 keV. This can now be done with NICER and AstroSat/LAXPC, which together are the largest X-ray instruments ever in the 0.3-80 keV band, and currently the only instruments with fast X-ray timing capability. Therefore, we propose for a total 100 ks of joint observations with NICER and AstroSat of two neutron star LMXBs, 4U 1636-536 and 4U 1820-30. These observations will provide new knowledge about kHz QPOs and burst oscillations, thus making a significant progress in understanding the fundamental physics of neutron stars. Besides, these observations will enable a unique fast-timing cross-calibration between two X-ray instruments.

Observations: We request 12kilo seconds on UVIT to observe dwarf irregular (dIrr) starburst galaxy, IC 10. Context: IC 10 is a local group dIrr that has an ongoing burst of star formation. It is unclear what triggers starbursts in dIrrs. Recently, two neutral hydrogen (HI) filaments were discovered in IC 10. Two starburst trigger mechanisms could explain the filaments: (1) a merger (2) accretion of intergalactic medium (IGM). Distinguishing between these scenarios will determine IC 10’s starburst trigger and which mechanisms are contributing to local galaxy building. IC 10 has the potential to become the first known case of IGM accretion. Objectives/Results: We will map the UV of IC 10. IGM would not be expected to harbor a young stellar population, resulting in no extra UV radiation. Tidal tails would be expected to have UV emission from the stellar population that was ejected from the disk during the tidal interaction.

Observations: We request 12kilo seconds on UVIT to observe dwarf irregular (dIrr) starburst galaxy, IC 10. Context: IC 10 is a local group dIrr that has an ongoing burst of star formation. It is unclear what triggers starbursts in dIrrs. Recently, two neutral hydrogen (HI) filaments were discovered in IC 10. Two starburst trigger mechanisms could explain the filaments: (1) a merger (2) accretion of intergalactic medium (IGM). Distinguishing between these scenarios will determine IC 10’s starburst trigger and which mechanisms are contributing to local galaxy building. IC 10 has the potential to become the first known case of IGM accretion. Objectives/Results: We will map the UV of IC 10. IGM would not be expected to harbor a young stellar population, resulting in no extra UV radiation. Tidal tails would be expected to have UV emission from the stellar population that was ejected from the disk during the tidal interaction.

Requested observation: One pointing in a Magellanic-Bridge GALEX-selected field. Context: Hot massive stars drive the chemical and dynamical evolution of their host galaxies, with feedback from their supersonic winds and supernova explosions, and copious yield of processed elements during their fast evolutionary time-scales. Their red-shifted UV light dominates the luminosity of distant objects. Understanding their evolution, especially at low metallicity, is key to interpret data of resolved and unresolved stellar populations. Current theories suffer from significant uncertainties, due to insufficient observational constraints. Objectives & Expected scientific results: UVIT imaging of a Magellanic-Bridge field, where GALEX shows abundance of hot stars, will uniquely enable us to derive a conclusive characterization of the young stellar population and dust. The proximity and stellar density of the field are ideal for a detailed mapping with UVIT resolution, complete for earliest-to-intermediate spectral types, and probing hot evolved objects for the first time.

We propose to do deep UV imaging of the merging galaxy MRK 212. The system shows dual cores and extended emission from tidal-tails at multi-wavelengths. We have observed MRK 212 in UVIT cycle A02 for 1.5 Ks. Our preliminary UVIT image has better resolution compared to GALEX. But the UV emission from outer disk and tidal tails are not detected. Hence we need deeper observations. The galaxy has been observed for ~9 Ks by GALEX. We estimate that a 15 Ks UVIT observation of MRK 212 will enable us to resolve the star-forming regions around the nuclei, the disk and tidal tails. We have studied the nuclei in MRK 212 using archival VLA radio data and found that one core is an active galactic nucleus while the other core could be an AGN or a star-forming region. We have obtained EVLA observing time to confirm the nature of the cores.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

The recent discovery of millisecond pulsars that swing between an accretion powered (X-ray) and a rotation powered (radio) pulsar state proved the evolutionary link between low-mass X-ray binaries and millisecond radio pulsars, and showed that transitions between the two regimes can be observed over timescales as short as a few weeks. Observing future X-ray outbursts of transitional millisecond pulsars will tell us whether the transitional phase is realized possible only for some binaries, and what are the details of the disk-agnetospheric interaction. We propose a 60 ks ASTROSAT ToO observation to detect the transition to an accretion state of a millisecond pulsar, by searching for X-ray coherent pulsations. Candidates were selected among millisecond radio pulsars whose radio signal is irregularly eclipsed. The proposed observation will also measure the long-term spin evolution of the pulsar, and follow its correlated flux-spectral variability over the 0.3-80 keV band.

Very few low-mass X-ray binaries show trains of regular, consistent bursts, but those that do are of high priority to observers, due to their utility in probing thermonuclear processes. We propose a 100~ks target-of-opportunity ASTROSAT observation of the long-interval transient 4U 0836-429, in order to comprehensively measure its observational properties. Our highest priority is to make measurements of frequent, long-duration thermonuclear bursts, to compare against numerical models and hence constrain the fuel composition and neutron star mass and radius. A secondary priority is observations in the "soft" spectral state, where radius-expansion bursts are expected, and from which we can constrain the source distance. At the same time, such bursts more frequently show burst oscillations, which have not been detected before from this source.

The blue straggler stars(BSS) are main-sequence(MS) stars, which have evaded stellar evolution by acquiring mass while on the MS. Primary mechanisms suggested for BSS formation in open clusters are (1) mass transfer from a binary and (2) merger of binaries. Gosnell et al. (2015) found that about 67% of blue stragglers are formed via mass transfer in the old open cluster NGC 188, by detecting WD companions to 7 BSS using the HST FUV observations. Accurate estimation of FUV flux is the main requirement to detect as well as estimate the temperature of WDs, in a BSS+WD binary. In the case of merger remnants, we do not expect to see a binary star or a WD as a companion. We plan to observe four nearby open star clusters older than 700 Myr to identify the fraction of BSS with WD binaries and to understand the properties of relatively massive BSS.

The blue straggler stars(BSS) are main-sequence(MS) stars, which have evaded stellar evolution by acquiring mass while on the MS. Primary mechanisms suggested for BSS formation in open clusters are (1) mass transfer from a binary and (2) merger of binaries. Gosnell et al. (2015) found that about 67% of blue stragglers are formed via mass transfer in the old open cluster NGC 188, by detecting WD companions to 7 BSS using the HST FUV observations. Accurate estimation of FUV flux is the main requirement to detect as well as estimate the temperature of WDs, in a BSS+WD binary. In the case of merger remnants, we do not expect to see a binary star or a WD as a companion. We plan to observe four nearby open star clusters older than 700 Myr to identify the fraction of BSS with WD binaries and to understand the properties of relatively massive BSS.

The blue straggler stars(BSS) are main-sequence(MS) stars, which have evaded stellar evolution by acquiring mass while on the MS. Primary mechanisms suggested for BSS formation in open clusters are (1) mass transfer from a binary and (2) merger of binaries. Gosnell et al. (2015) found that about 67% of blue stragglers are formed via mass transfer in the old open cluster NGC 188, by detecting WD companions to 7 BSS using the HST FUV observations. Accurate estimation of FUV flux is the main requirement to detect as well as estimate the temperature of WDs, in a BSS+WD binary. In the case of merger remnants, we do not expect to see a binary star or a WD as a companion. We plan to observe four nearby open star clusters older than 700 Myr to identify the fraction of BSS with WD binaries and to understand the properties of relatively massive BSS.

The blue straggler stars(BSS) are main-sequence(MS) stars, which have evaded stellar evolution by acquiring mass while on the MS. Primary mechanisms suggested for BSS formation in open clusters are (1) mass transfer from a binary and (2) merger of binaries. Gosnell et al. (2015) found that about 67% of blue stragglers are formed via mass transfer in the old open cluster NGC 188, by detecting WD companions to 7 BSS using the HST FUV observations. Accurate estimation of FUV flux is the main requirement to detect as well as estimate the temperature of WDs, in a BSS+WD binary. In the case of merger remnants, we do not expect to see a binary star or a WD as a companion. We plan to observe four nearby open star clusters older than 700 Myr to identify the fraction of BSS with WD binaries and to understand the properties of relatively massive BSS.

In recent, very successful coordinated multiwavelength campaigns on several Galactic black hole X-ray binaries, we have detected fast sub-second optical and infrared variability and remarkable multiwavelength timing correlations. These rule out a reprocessing origin for the optical fluxes. Instead, the data support a scenario where the rapid optical variations arise at the jet base, thereby allowing fundamental, quantitative constraints on the extensions of relativistic jets in compact objects. But such constraints exist for less than a handful of objects. Here, we propose to extend such constraints with anticipated ToO observations of up to 2 hard state outbursts with AstroSat strictly simultaneous with ground-based optical/infrared timing. We will probe rapid, sub-second photometric variations and search for inter-band time delays to disentangle the jet/disc/coronal components using spectral-timing. We additionally propose to test and calibrate UVIT timing mode.

In recent, very successful coordinated multiwavelength campaigns on several Galactic black hole X-ray binaries, we have detected fast sub-second optical and infrared variability and remarkable multiwavelength timing correlations. These rule out a reprocessing origin for the optical fluxes. Instead, the data support a scenario where the rapid optical variations arise at the jet base, thereby allowing fundamental, quantitative constraints on the extensions of relativistic jets in compact objects. But such constraints exist for less than a handful of objects. Here, we propose to extend such constraints with anticipated ToO observations of up to 2 hard state outbursts with AstroSat strictly simultaneous with ground-based optical/infrared timing. We will probe rapid, sub-second photometric variations and search for inter-band time delays to disentangle the jet/disc/coronal components using spectral-timing. We additionally propose to test and calibrate UVIT timing mode.

In recent, very successful coordinated multiwavelength campaigns on several Galactic black hole X-ray binaries, we have detected fast sub-second optical and infrared variability and remarkable multiwavelength timing correlations. These rule out a reprocessing origin for the optical fluxes. Instead, the data support a scenario where the rapid optical variations arise at the jet base, thereby allowing fundamental, quantitative constraints on the extensions of relativistic jets in compact objects. But such constraints exist for less than a handful of objects. Here, we propose to extend such constraints with anticipated ToO observations of up to 2 hard state outbursts with AstroSat strictly simultaneous with ground-based optical/infrared timing. We will probe rapid, sub-second photometric variations and search for inter-band time delays to disentangle the jet/disc/coronal components using spectral-timing. We additionally propose to test and calibrate UVIT timing mode.

In recent, very successful coordinated multiwavelength campaigns on several Galactic black hole X-ray binaries, we have detected fast sub-second optical and infrared variability and remarkable multiwavelength timing correlations. These rule out a reprocessing origin for the optical fluxes. Instead, the data support a scenario where the rapid optical variations arise at the jet base, thereby allowing fundamental, quantitative constraints on the extensions of relativistic jets in compact objects. But such constraints exist for less than a handful of objects. Here, we propose to extend such constraints with anticipated ToO observations of up to 2 hard state outbursts with AstroSat strictly simultaneous with ground-based optical/infrared timing. We will probe rapid, sub-second photometric variations and search for inter-band time delays to disentangle the jet/disc/coronal components using spectral-timing. We additionally propose to test and calibrate UVIT timing mode.

In recent, very successful coordinated multiwavelength campaigns on several Galactic black hole X-ray binaries, we have detected fast sub-second optical and infrared variability and remarkable multiwavelength timing correlations. These rule out a reprocessing origin for the optical fluxes. Instead, the data support a scenario where the rapid optical variations arise at the jet base, thereby allowing fundamental, quantitative constraints on the extensions of relativistic jets in compact objects. But such constraints exist for less than a handful of objects. Here, we propose to extend such constraints with anticipated ToO observations of up to 2 hard state outbursts with AstroSat strictly simultaneous with ground-based optical/infrared timing. We will probe rapid, sub-second photometric variations and search for inter-band time delays to disentangle the jet/disc/coronal components using spectral-timing. We additionally propose to test and calibrate UVIT timing mode.

We wish to observe two embedded clusters (ECs) (Camargo 438 and Camargo 439) within the high-latitude molecular cloud HRK $81.4~H~R77$. This is the first detection of star formation in a high latitude molecular cloud, hence making them very interesting targets of study. Our Primary instrument is UVIT - NUV, with UVIT-FUV as the secondary instrument. As these are very young clusters ~2 Myr, we expect UV radiation from the stars. Also young stars are copius emitters of Xrays and hence we also plan observations using from SXT, LAXPC, and CZTI.

We wish to observe two embedded clusters (ECs) (Camargo 438 and Camargo 439) within the high-latitude molecular cloud HRK $81.4~H~R77$. This is the first detection of star formation in a high latitude molecular cloud, hence making them very interesting targets of study. Our Primary instrument is UVIT - NUV, with UVIT-FUV as the secondary instrument. As these are very young clusters ~2 Myr, we expect UV radiation from the stars. Also young stars are copius emitters of Xrays and hence we also plan observations using from SXT, LAXPC, and CZTI.

We wish to observe two embedded clusters (ECs) (Camargo 438 and Camargo 439) within the high-latitude molecular cloud HRK $81.4~H~R77$. This is the first detection of star formation in a high latitude molecular cloud, hence making them very interesting targets of study. Our Primary instrument is UVIT - NUV, with UVIT-FUV as the secondary instrument. As these are very young clusters ~2 Myr, we expect UV radiation from the stars. Also young stars are copius emitters of Xrays and hence we also plan observations using from SXT, LAXPC, and CZTI.

The globular cluster Terzan 5 contains numerous transient low-mass X-ray binaries. At least three of these have undergone X-ray outbursts over the past 15 years, showing a variety of intriguing behaviours. We propose a 40 ks AstroSAT observation of the next bright outburst from Terzan 5, to measure its X-ray energy spectrum, characterize its power spectrum, search for pulsations, and study any X-ray bursts that occur.

We request observations of the TeV blazar, PKS0447-439, using the multiwavelength instruments on board the ASTROSAT. We propose for 1 snapshot of 40 ks for this source.The redshift of this blazar is under debate. The proposed observation will provide unprecedented simultaneous UV/X-ray observations. This will be complemented by observations at optical, GeV and TeV measurements from other space and ground based satellites. This will give a complete sampling of the SED, and will provide us with hitherto unknown clues on the physical processes responsible for the outbursts in blazars. More importantly, simultaneous X-ray/TeV measurements will be crucial in constraining the redshift of this blazar.

We propose to map the UV emission around dual nuclei in late stage galaxy mergers and interacting systems. Mergers can trigger bursts of star-formation and nuclear activity in galaxies. This can result in dual AGN and AGN+star-forming nuclei in the merging galaxies. Our targets have been observed by GALEX but not with the Hubble Space Telescope (HST) UVIS camera. The higher spatial resolution of UVIT compared to GALEX will help us resolve the dual cores and study the disk star-formation triggered by the merging process. Our targets are all low redshift, UV bright sources. We will confirm the nature of the double cores, map the associated star-formation, estimate star-formation rates and its correlation with the different types of nuclei. Not much is known about the UV emission from dual AGN/starburst nuclei; hence UVIT observations will be an important step for understanding galaxy mergers.

We propose to map the UV emission around dual nuclei in late stage galaxy mergers and interacting systems. Mergers can trigger bursts of star-formation and nuclear activity in galaxies. This can result in dual AGN and AGN+star-forming nuclei in the merging galaxies. Our targets have been observed by GALEX but not with the Hubble Space Telescope (HST) UVIS camera. The higher spatial resolution of UVIT compared to GALEX will help us resolve the dual cores and study the disk star-formation triggered by the merging process. Our targets are all low redshift, UV bright sources. We will confirm the nature of the double cores, map the associated star-formation, estimate star-formation rates and its correlation with the different types of nuclei. Not much is known about the UV emission from dual AGN/starburst nuclei; hence UVIT observations will be an important step for understanding galaxy mergers.

Magnetic cataclysmic variables show strong variations in their emitted radiation due to the changes in the flow of accretion matter impacting on the magnetic white dwarfs. The interactions of the ionized accretion matter with the magnetic field and the effective cooling of the hot plasma on the white dwarf surface are the key issues to explain the variability but these are not well understood. Here we propose to study the accretion flow characteristics close to the white dwarf surface. The multi-wavelength observations using ASTROSAT and SAAO/SALT will provide the information about the accretion flow geometry near the surface, the cooling mechanism of the hot accreted material. The orbital period and the white dwarf mass can also be constrained with better accuracy.

Magnetic cataclysmic variables show strong variations in their emitted radiation due to the changes in the flow of accretion matter impacting on the magnetic white dwarfs. The interactions of the ionized accretion matter with the magnetic field and the effective cooling of the hot plasma on the white dwarf surface are the key issues to explain the variability but these are not well understood. Here we propose to study the accretion flow characteristics close to the white dwarf surface. The multi-wavelength observations using ASTROSAT and SAAO/SALT will provide the information about the accretion flow geometry near the surface, the cooling mechanism of the hot accreted material. The orbital period and the white dwarf mass can also be constrained with better accuracy.

We request 50~ks ASTROSAT observations of the intermediate polar FO Aqr to study the current accretion state of the source. This previously known steady source has recently gone into the low state in May 2016 and now it is recovering from there. The optical light curve indicates the almost full recovery in January 2017. The multi-wavelength observation will provide the current accretion characteristics i.e. the accretion mode (disc-fed/stream-fed), the accretion flow geometry near the surface, any change in spin and orbital period.

We propose a multi wavelength observation of two Bl Lac objects, H 1426+428 and PKS 0521-36 using the multiwavelength payloads on board ASTROSAT. We request for single pointing of 30 ks for each source, resulting a total observation of 60 ks. The combined UVIT-SXT observation can be used to probe the synchrotron tail of the broadband spectral energy distribution (SED). The knowledgeof the high energy synchrotron spectrum is important for understanding a meaningful radiative model for the source. The hard X-ray region, which can be probed by LAXPC, in the both sources. Further multiwavelength observation by ASTROSAT can be combined with Fermi-LAT observation to study over all emission and model SED. With this we can constrain the underlying model parameters responsible for the emission. Also using the multi-wavelength observation we will constrain the seed photon responsible for the inverse Compton process during the source detection.

We propose a 45 ks effective exposure of BHC XTE J1908+094 using LAXPC & SXT in- struments on-board the AstroSat satellite. The source is a jet emitting transient LMXB discovered by RXTE/PCA and it continues to be persistent. The broadband tempo-spectral studies by RXTE, Bepposax, NuStar, Swift & Maxi observatories indicate the BH nature of the source. We propose to study the quasi-periodicity, its evolution, X-ray states, accretion and radio connection. LAXPC and SXT data will help in confirming black hole spin parameter by studying the relativistic smearing of Fe Ka line of XTE J1908+094. Temporal variability of the source is unexplored above 20 keV. LAXPC together with SXT is an ideal instrument to study energy dependent timing variabilities in 0.3-80 keV energy band, which will further confirm the BH nature of the source.

Observations suggest that active galactic nuclei (AGN) play a central role in the galaxy evolution process via feedback mechanism. The alignment of radio/UV structures in high redshift radio galaxies led to the idea of jet-induced star formation. However, the local universe is mainly populated by radio faint galaxies. Observations of such AGN in this respect are found to be lacking. Hence, we aim to search for jet induced star formation in the low redshift universe using the high resolution capabilities of UVIT. Towards this, we propose to observe three low redshift AGN to identify star-forming regions, derive their physical parameters and investigate if jets indeed play a role in triggering star formation in low redshift AGN. This will be done in conjunction with radio (VLA/GMRT) and X-ray (Chandra) data. We request for a total observing time of 60 ksec for the three sources with UVIT as the prime instrument.

We propose AO observations of the TeV blazar PKS 1510-089 using various instruments along with, UVIT, SXT, LAXPC and CZTI on-board AstroSat. In this proposal, we are requesting for two observations of 30 ks (with SXT as prime instrument) having a total observation time of 60 ks which will give a X-ray spectrum with good statistical significance. We are also planning to organize a multiwaveband campaign using H.E.S.S, MAGIC telescopes, Fermi-LAT and Swift-XRT. Detection of X-ray and TeV variability, along with correlation studies between different energy bands from UV to $\gamma$-rays will provide unprecedented knowledge about the origin of X-ray and $\gamma$-ray emission in the source. The broadband SED obtained from simultaneous or quasi-simultaneous MWL observations will give crucial information about the physical properties of the source.

We propose to make a long duration ($\sim$ 10 days) observation of the active galaxy MCG-6-30-15. The AGN is known to show significant spectral variability on all timescales. We wish to use this variability to constrain the primary emission mechanisms, their location and their relative geometry. We would thus hope to obtain a better understanding of the accretion disk, its corona and the distributions of circum-nuclear matter in these esoteric objects.

Study of $\Gamma_x-L/L_{edd}$ relation in Seyfert galaxies is one way of establishing the connection between basic properties of accreting supermassive black holes and the emergent continuum radiation. Several studies carried out in the past mainly used spectral shape obtained from soft X-ray spectra. AstroSat gives an unique opportunity to study spectral shape over the wider band of 0.3-100 keV, which will enable us to constrain the $\Gamma_x-L/L_{edd}$ relation. We have identified a sample of hard X-ray (Swift/BAT) selected bright Seyfert galaxies with measured mass and propose 20 ks (each) observations of four bright type 1 Seyferts to augment this sample with a precise measurement of the spectral shape. We also plan to study the short term X-ray variability in these objects.

Study of $\Gamma_x-L/L_{edd}$ relation in Seyfert galaxies is one way of establishing the connection between basic properties of accreting supermassive black holes and the emergent continuum radiation. Several studies carried out in the past mainly used spectral shape obtained from soft X-ray spectra. AstroSat gives an unique opportunity to study spectral shape over the wider band of 0.3-100 keV, which will enable us to constrain the $\Gamma_x-L/L_{edd}$ relation. We have identified a sample of hard X-ray (Swift/BAT) selected bright Seyfert galaxies with measured mass and propose 20 ks (each) observations of four bright type 1 Seyferts to augment this sample with a precise measurement of the spectral shape. We also plan to study the short term X-ray variability in these objects.

Study of $\Gamma_x-L/L_{edd}$ relation in Seyfert galaxies is one way of establishing the connection between basic properties of accreting supermassive black holes and the emergent continuum radiation. Several studies carried out in the past mainly used spectral shape obtained from soft X-ray spectra. AstroSat gives an unique opportunity to study spectral shape over the wider band of 0.3-100 keV, which will enable us to constrain the $\Gamma_x-L/L_{edd}$ relation. We have identified a sample of hard X-ray (Swift/BAT) selected bright Seyfert galaxies with measured mass and propose 20 ks (each) observations of four bright type 1 Seyferts to augment this sample with a precise measurement of the spectral shape. We also plan to study the short term X-ray variability in these objects.

We propose a $\sim$50~ks Astrosat observation of the eclipsing X-ray transient IGR~J17451-3022 to investigate the nature of the poorly studied X-ray source in the binary system. Due to the detection of X-ray eclipses in its light curve and short orbital period ($\sim$6.3~hr), IGR~J17451-3022 is believed to be a low-mass X-ray binary. Using the proposed observation, we will investigate the timing and broadband spectral properties of the source in detail which has not been done yet. The Astrosat observation will allow us to constrain the color-color and hardness intensity diagrams that would be crucial for identifying the nature of the compact object. Spectral characteristics with SXT and LAXPC will help us to understand the origin of high energy emission, inner accretion disk size which can provide information on the central source. This observation will also estimate the eclipse parameters with better accuracy as well as constrain the mass ratio.

Recently discovered gamma-ray/Be binary pulsar PSR J2032+4127, with an orbital period of ~50 years, is known to be approaching the periastron in late 2017/ early 2018. We propose a ~40 ks Astrosat observation of the pulsar at its periastron passage during November 2017 -- January 2018. Using the proposed Astrosat observation, we will investigate the mechanism of high energy emission, flares, presence or absence of X-ray pulsation, wind dynamics of the pulsar, stellar wind properties, disk-outflow, and neutron star interaction with Be circumstellar disk. Coordinated continuous optical/ near-infrared monitoring observations of the Be star will also be carried out by using the 2.1~m Mexican and 1.2~m Mt. Abu telescopes, in addition to TeV observations with HAWC. These multiwavelength observations are essential to understanding the evolution, interaction, and dynamics of neutron star with Be-disk in the gamma-ray binary.

SWIFT J1749.4-2807 is an eclipsing accreting millisecond X-ray pulsar~(AMXP) having tight constraints on its inclination range (~74.4-77.3 degree). It is a unique AMXP that shows double peaked pulse profiles during its outbursts and most importantly, it shows uncommonly strong harmonic content that, together with the known inclination, suggests that it might be the best source to date to set constraints on neutron star properties including compactness and geometry. To further explore this possibility we propose to observe the next outburst of SWIFT J1749.4--2807 with 40 ksec. We aim at performing pulse profile evolution study and to model these pulse profiles to constrain Equation of State (EOS) models. We will also perform spectral study of this source using X-ray data of the ASTROSAT (SXT+LAXPC). This will be complemented by an extensive Swift monitoring of the new outburst.

Black hole X-ray binaries cycle through different accretion states on timescales of days to months, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous observations across the electromagnetic spectrum are the optimal tool that exposes this view. However, strictly simultaneous radio through broad-band X-ray observations have been achieved in only a few X-ray binary outbursts. We request six 20 ks epochs of ASTROSAT (LAXPC/SXT/CZTI) observations of GX~339-4. We will trigger two sequences of 15-day monitoring over three epochs each, for which we will coordinate multi-wavelength coverage, to measure the evolving broad-band spectral energy distributions (SEDs) during the rising-hard and decaying-hard accretion states. We will determine how the evolving accretion properties (derived from X-ray timing and fitting models to X-ray spectra) are connected to the evolving jet properties (derived from broad-band SED fits that constrain, for example, the conditions where the electrons are first accelerated).

Black hole X-ray binaries cycle through different accretion states on timescales of days to months, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous observations across the electromagnetic spectrum are the optimal tool that exposes this view. However, strictly simultaneous radio through broad-band X-ray observations have been achieved in only a few X-ray binary outbursts. We request six 20 ks epochs of ASTROSAT (LAXPC/SXT/CZTI) observations of GX~339-4. We will trigger two sequences of 15-day monitoring over three epochs each, for which we will coordinate multi-wavelength coverage, to measure the evolving broad-band spectral energy distributions (SEDs) during the rising-hard and decaying-hard accretion states. We will determine how the evolving accretion properties (derived from X-ray timing and fitting models to X-ray spectra) are connected to the evolving jet properties (derived from broad-band SED fits that constrain, for example, the conditions where the electrons are first accelerated).

%latex%The typical AGN spectra is complex with having a soft excess which dominates in low energies while at high energies the spectrum is believed to be due to thermal Comptonization. While earlier studies have been typically limited to narrow energy bands, AstroSat provides a unique opportunity to study the complete broad band X-ray spectrum (0.3-80 keV) which covers all the spectral components and hence to understand the relation between them. The simultaneous multi-wavelength capability of AstroSat can better constrain the SED fit with UVIT observations in the optical/UV band. We propose a 40 ksec observation of the well known Seyfert 1 galaxy Mrk 279 with SXT as the primary instrument along with LAXPC and UVIT. These observations will also help to study the possible fast variability in short timescales of the source in both UV and X-ray bands.

We propose a monitoring campaign of LMC X-3 with 4 observations of 15 ks each separated by 15 days with AstroSat using SXT as the primary instrument. This will be a multi-wavelength study of the intensity variations in LMC X-3. The source displays large variations in intensity with associated change of state in these variations in a large waveband from infrared to X-rays. Time lags are present in between different bands. However, there has been no systematic study of these lags across the UV, X-ray waveband. With this proposal, we intend to study the wide-band spectrum of the binary in different states and also monitor the lags in the intensity variations using the excellent timing and spectral coverage of AstroSat. With this information, we will model the accretion geometry (wind/disk based) as a function of the orbit of this source using techniques developed in Iyer et~al (2015).

Requested observation: UVIT imaging of three bright nearby star-forming galaxies for which we have assembled a unique array of panchromatic photometry. Context: A majority of the dust in galaxies is cold, and very difficult to detect. This is unfortunate, because a precise understanding of dust is essential to a correct understanding of galaxies’ young stellar content and their far-infrared emission commonly associated with ongoing star formation. Objectives & Expected scientific results : Our proposed UVIT imaging will bracket the Balmer break and thereby measure precisely the ages of the young stellar populations in our sources. This will in turn identify the portion of the thermal far-IR emission associated with young stars, and reveal the hitherto hidden cold dust.

Requested observation: UVIT imaging of three bright nearby star-forming galaxies for which we have assembled a unique array of panchromatic photometry. Context: A majority of the dust in galaxies is cold, and very difficult to detect. This is unfortunate, because a precise understanding of dust is essential to a correct understanding of galaxies’ young stellar content and their far-infrared emission commonly associated with ongoing star formation. Objectives & Expected scientific results : Our proposed UVIT imaging will bracket the Balmer break and thereby measure precisely the ages of the young stellar populations in our sources. This will in turn identify the portion of the thermal far-IR emission associated with young stars, and reveal the hitherto hidden cold dust.

Requested observation: UVIT imaging of three bright nearby star-forming galaxies for which we have assembled a unique array of panchromatic photometry. Context: A majority of the dust in galaxies is cold, and very difficult to detect. This is unfortunate, because a precise understanding of dust is essential to a correct understanding of galaxies’ young stellar content and their far-infrared emission commonly associated with ongoing star formation. Objectives & Expected scientific results : Our proposed UVIT imaging will bracket the Balmer break and thereby measure precisely the ages of the young stellar populations in our sources. This will in turn identify the portion of the thermal far-IR emission associated with young stars, and reveal the hitherto hidden cold dust.

We request AO observations of the three radio galaxies Cen A, M87 and NGC 1275 using the multiwavelength instruments (SXT, LAXPC, CZTI \& UVIT) on board AstroSat. We are asking for two pointings of 30 ks effective exposure for each observation i.e. a total exposure of 60 ks per source with SXT as a primary instrument. The nature of the X-ray flux variability and spectrum will provide very crucial information about the origin of the X-ray and $\gamma$-ray emission from the source.

We propose to carry out an in-depth multi-band study of an active, ultra-fast rotator AB Dor with a rotation period of 0.51 days. The K-type main sequence star, at a distance of 14.9 pc displays very high X-ray flaring frequency of ~2 flares per rotation, with numerous strong flares on time scales from minutes to weeks, which reaches upto an integrated X-ray fluxes of ~4x10^{-9} erg cm^{-2} s^{-1}. However, a detailed study of AB Dor in hard X-ray band was not been carried out, thus far. We intend to study the highly time-resolved correlation of photospheric, chromospheric and coronal activity indicators and to study the rotational modulation. These proposed observations will allow us to understand the dynamic behavior of the corona, which is found to be strongly related to the fluorescence of the photospheric materials. Furthermore, the proposed observations will yield insight into the nature of the associated magnetic dynamos.

We propose a 70-ks ASTROSAT observation of the fastest accreting millisecond pulsar IGR J00291+5934 during its next outburst. We aim at measuring the spin and orbital parameters of this interesting source, in order to improve its ephemeris. This is the only accreting millisecond pulsar for which there is a general agreement on the spin-up observed during outbursts. It also shows a long-term spin-down, probably caused by magnetic dipole emission during quiescent periods or gravitational radiation from the fast spinning neutron star. The next outburst will allow us to constrain the still elusive orbital period derivative in this systems, and its long-term orbital evolution, or to give very tight upper limits. The knowledge of accurate and precise ephemeris of the pulsar are of paramount importance for a meaningful search of the radio and gamma-ray counterparts expected to turn on if the source switches to a rotation-powered pulsar state during X-ray quiescence.

A 50 ks observation of the persistent atoll source GX 3+1 with LAXPC as the primary instrument is proposed. The object is one of the brightest atoll sources and switches between bright and faint phases. Since LAXPC can measure the time lags as small as few tens of milli-seconds, the frequency resolved time lags and its energy dependence will help us understand the interplay between the hard and soft photons and the origin of hard X-ray emission which is believed to be originated in the transition layer between accretion disk and the neutron star. Simultaneous coverage with SXT, LAXPC and CZTI will be helpful in the characterization of the spectral models.

We request a 50 ks {\it AstroSat} observation (with UVIT as primary instrument) of a bare NLS1 UGC~06728. This AGN exhibits strong and rapid variabilities in the UV/optical and X-ray bands. These variations have never been studied in detail till date in this AGN. Existing X-ray/UV/Optical observations of the AGN do not allow us for cross-correlation analysis to investigate the cause of observed variabilities. To carry out such studies in detail, simultaneous multiwavelength observations are very much essential. Considering this, we propose a single long observation with the UVIT, SXT, LAXPC and CZTI instruments of {\it AstroSat}. Simultaneous Optical/IR observations of the AGN will be carried out by using IR observatory of PRL and other ground based observatories in India. The main aim of this proposal is to study the correlation between the UV/optical/IR and X-ray bands, and to derive the lag spectrum to understand the nature of accretion disk.

A 50 ks observation of the persistent atoll source 4U 1735-44 with LAXPC as the primary instrument is proposed. The object is a bright atoll source and switches between various branches in color-color diagram. The object’s brightness and LAXPC’s capability of measuring time lags as small as few tens of milli-seconds can be harnessed to study frequency resolved time lags and its energy dependence. The analysis of timelags and cross correlation functions will be used to analyse the relation between different energy bands, which in turn will help to understand radiative processes and accretion flow properties. A systematic search will be made to detect kHz QPO which has been detected in RXTE data of the object. Simultaneous coverage with SXT, LAXPC, and CZTI will be helpful in the characterisation of spectral models.

As blazars are extremely variable objects emitting radiation along the electromagnetic spectrum, simultaneous multi-wavelength observations are crucial. To fully characterize their behaviour and draw conclusions on the underlying physics, it is important to study the temporal behaviour of the spectral energy distribution. We chose a sample of blazars with different properties which are being monitored at very high energies. We propose to monitor this sample with ASTROSAT with a two week cadence to collect an unprecedented multi-wavelength data sample which will allow us to better describe the spectral energy distribution making use of the multi-wavelength capabilities of ASTROSAT. Combining it with the gamma-ray data, we will be able to study the correlation of the two energy ranges which allows us to constrain theoretical models on the emission mechanisms for the highest energies. For the whole sample of four sources, we propose a total exposure of 140 ks.

As blazars are extremely variable objects emitting radiation along the electromagnetic spectrum, simultaneous multi-wavelength observations are crucial. To fully characterize their behaviour and draw conclusions on the underlying physics, it is important to study the temporal behaviour of the spectral energy distribution. We chose a sample of blazars with different properties which are being monitored at very high energies. We propose to monitor this sample with ASTROSAT with a two week cadence to collect an unprecedented multi-wavelength data sample which will allow us to better describe the spectral energy distribution making use of the multi-wavelength capabilities of ASTROSAT. Combining it with the gamma-ray data, we will be able to study the correlation of the two energy ranges which allows us to constrain theoretical models on the emission mechanisms for the highest energies. For the whole sample of four sources, we propose a total exposure of 140 ks.

As blazars are extremely variable objects emitting radiation along the electromagnetic spectrum, simultaneous multi-wavelength observations are crucial. To fully characterize their behaviour and draw conclusions on the underlying physics, it is important to study the temporal behaviour of the spectral energy distribution. We chose a sample of blazars with different properties which are being monitored at very high energies. We propose to monitor this sample with ASTROSAT with a two week cadence to collect an unprecedented multi-wavelength data sample which will allow us to better describe the spectral energy distribution making use of the multi-wavelength capabilities of ASTROSAT. Combining it with the gamma-ray data, we will be able to study the correlation of the two energy ranges which allows us to constrain theoretical models on the emission mechanisms for the highest energies. For the whole sample of four sources, we propose a total exposure of 140 ks.

The ultraviolet and X-ray emissions in AGN are often inter-connected. We plan to study the UV and X-ray variability of the NLS1 galaxy Mrk 335 using the simultaneous multiwavelength observational facility of ASTROSAT. We propose for a monitoring observation of Mrk 335 on 8 occasions, each separated by minimum 15 days, in both X-ray and UV bands. We request to observe the source for an individual exposure time of 19 ks with UVIT (primary instrument), simultaneously with SXT and LAXPC. The study will be useful to understand the geometry of the innermost regions of the AGN.

$\gamma$-rays are expected to be originated in AGN jet. As emission from jet falls off rapidly with jet inclination angle, misaligned AGNs (M-AGNs) are expected to be weak $\gamma$-ray emitter.One of the source, NGC 1275, will be observed under accepted AO3 proposal. Here, we propose to observe the nearest Fermi detected FR II radio galaxy Pictor A, under AO4 observing period. In this source distinct core, jet and hotspot has been observed in radio and optical waveband. High resolution image from UV will be crucial to understand structure and morphology of jet and hotspot in multiband. We propose simultaneous observation of Pictor A with UVIT, SXT along with LAXPC and CZTI detectors on board ASTROSAT which is essential to construct the broadband spectra of the source and to better understand site of origin of $\gamma$-rays and the accretion disk-AGN jet connection.

The origin of optical/UV variations and the nature of accretion disks in AGN have been long standing problems. Recent Swift monitoring of a handful of AGN with low relative accretion rates reveal that the variations in optical/UV emission are caused by reprocessing of X-rays in the disk and the optical/UV lags are about 3 times longer than that expected for standard Shakura-Sunyaev disks. Measurement of optical/UV lags in high accretion rate AGN is lacking. We propose to measure time-lag, as a function of wavelength, between the optical/UV and X-ray emission, in a low mass, high accretion rate, bright and nearly absorption-free narrow-line Seyfert 1 galaxy Mrk1044. We request 150~ks AstroSat observation, with SXT as the primary instrument. We will also perform ground-based optical observations in parallel with our AstroSat observation. We will investigate the driver of optical/UV variations and test if this high acccretion rate AGN hosts a standard disk.

We propose to observe the broad line radio galaxy 3C 111 for 100 ks continuously. Previous work of the PI showed that at ~days-months timescales X-ray/optical variability in 3C 111 is due directly or indirectly to intrinsic thermal fluctuations in the accretion disk. However, at shorter timescales (~hr) optical-UV variability may be due to intrinsic fluctuation in coronal X-rays and reprocessing of the X-rays at the disk. In that case we expect to observe fluctuation in the optical-UV emission of 3C 111 following that at the X-rays by a few hours. We plan to test this hypothesis with the proposed Astrosat observations and simultaneous ground based optical monitoring. Furthermore, the nature of soft-hard X-ray time lag (if any), and relative variability at X-ray and optical bands may help constrain the size and location of the corona.

The mechanism by which disc is formed is classical Be stars, known as ‘Be phenomenon’, is one of the open puzzles in stellar research (Rivinius et al. 2013). One of the often suggested mechanisms is the role of an ‘invisible’ companion in the formation of this disc (Porter & Rivinius 2003). By 'invisible’ companion we mean the companion whose presence is not easily assessed from continuum emission or spectral features in optical/infrared. They make their presence felt in the far-UV and X-ray region of the electromagnetic spectrum. Our proposal is to search for the elusive Be binary systems with white-dwarf (WD) or subdwarf O-type star (sdO or helium star) being the companion to Be star. However, no Be-WD system is detected till now and only a few (about 4) binaries belonging to Be-sdO category. Observations with UVIT and SXT are proposed to identify the hidden companions associated with Be stars.

The mechanism by which disc is formed is classical Be stars, known as ‘Be phenomenon’, is one of the open puzzles in stellar research (Rivinius et al. 2013). One of the often suggested mechanisms is the role of an ‘invisible’ companion in the formation of this disc (Porter & Rivinius 2003). By 'invisible’ companion we mean the companion whose presence is not easily assessed from continuum emission or spectral features in optical/infrared. They make their presence felt in the far-UV and X-ray region of the electromagnetic spectrum. Our proposal is to search for the elusive Be binary systems with white-dwarf (WD) or subdwarf O-type star (sdO or helium star) being the companion to Be star. However, no Be-WD system is detected till now and only a few (about 4) binaries belonging to Be-sdO category. Observations with UVIT and SXT are proposed to identify the hidden companions associated with Be stars.

The mechanism by which disc is formed is classical Be stars, known as ‘Be phenomenon’, is one of the open puzzles in stellar research (Rivinius et al. 2013). One of the often suggested mechanisms is the role of an ‘invisible’ companion in the formation of this disc (Porter & Rivinius 2003). By 'invisible’ companion we mean the companion whose presence is not easily assessed from continuum emission or spectral features in optical/infrared. They make their presence felt in the far-UV and X-ray region of the electromagnetic spectrum. Our proposal is to search for the elusive Be binary systems with white-dwarf (WD) or subdwarf O-type star (sdO or helium star) being the companion to Be star. However, no Be-WD system is detected till now and only a few (about 4) binaries belonging to Be-sdO category. Observations with UVIT and SXT are proposed to identify the hidden companions associated with Be stars.

The mechanism by which disc is formed in classical Be stars is one of the open puzzles in stellar research. One of the often suggested mechanisms is the role of an ‘invisible’ hot companion in the formation of this disc. They make their presence felt in the UV and X-ray region of the electromagnetic spectrum. Our proposal is to search for the elusive Be binary systems with whitedwarf or subdwarf O-type star being the companion to Be star. Mathew et al.(2008) identified few Be stars in the open clusters NGC 7510, NGC 7128 and NGC 581. The NUV magnitudes from GALEX data shows that most of these Be stars are brighter in the NUV, when compared to Be stars in other clusters which is suggestive of a hot companion. We plan to image these clusters in the FUV and NUV filters to measure, detect and characterize the UV excess.

The mechanism by which disc is formed in classical Be stars is one of the open puzzles in stellar research. One of the often suggested mechanisms is the role of an ‘invisible’ hot companion in the formation of this disc. They make their presence felt in the UV and X-ray region of the electromagnetic spectrum. Our proposal is to search for the elusive Be binary systems with whitedwarf or subdwarf O-type star being the companion to Be star. Mathew et al.(2008) identified few Be stars in the open clusters NGC 7510, NGC 7128 and NGC 581. The NUV magnitudes from GALEX data shows that most of these Be stars are brighter in the NUV, when compared to Be stars in other clusters which is suggestive of a hot companion. We plan to image these clusters in the FUV and NUV filters to measure, detect and characterize the UV excess.

The mechanism by which disc is formed in classical Be stars is one of the open puzzles in stellar research. One of the often suggested mechanisms is the role of an ‘invisible’ hot companion in the formation of this disc. They make their presence felt in the UV and X-ray region of the electromagnetic spectrum. Our proposal is to search for the elusive Be binary systems with whitedwarf or subdwarf O-type star being the companion to Be star. Mathew et al.(2008) identified few Be stars in the open clusters NGC 7510, NGC 7128 and NGC 581. The NUV magnitudes from GALEX data shows that most of these Be stars are brighter in the NUV, when compared to Be stars in other clusters which is suggestive of a hot companion. We plan to image these clusters in the FUV and NUV filters to measure, detect and characterize the UV excess.

We propose a 40 ks ASTROSAT observation of IGR J13020–6359 that is member of a newly emerging sub-class of Be X-ray Binary (BeXRB) pulsars. Most BeXRBs are transient sources showing rapid spin-up during the outbursts and relatively slow spin down during quiescence. A relatively newly known subclass of BeXRBs show persistent and low luminosity level, perhaps due to persistent accretion from a low density wind, rather than the outflowing disk of the Be Star. Two characteristics that make IGR J13020–6359 unique are its persistent nature yet a strong, steady spin up for the last 20 years. In the standard theory of accretion onto high magnetic field neutron stars, steady spin up should result from either a high X-ray luminosity or a very low magnetic field strength of the neutron star. With the proposed ASTROSAT observation we will make a detailed broad band timing and spectral characterisation of this understudied source.

Dipping X-ray sources show the prescence of a low frequency QPO which is called the 1 Hz QPO. The properties of this QPO are different than those of other low frequency oscillations detected in X-ray binaries. This QPO is detected with equal amplitude (rms) during bursts, persistent emission and dips. Unlike othe low frequency QPOs its does not show any dependence on the energy, however this was within the sensitivity and energy range of RXTE/PCA. We propose to investigate the rms-energy spectra of 1 Hz QPOs with the wide energy range and higher sensitivity of Astrosat/LAXPC, we request 10 observations during the hard state of the source in this anticipated ToO. This will lead to the understanding of whether 1 Hz QPOs have origins in the Lenz-Thirring precession as proposed.

Dipping X-ray sources show the prescence of a low frequency QPO which is called the 1 Hz QPO. The properties of this QPO are different than those of other low frequency oscillations detected in X-ray binaries. This QPO is detected with equal amplitude (rms) during bursts, persistent emission and dips. Unlike othe low frequency QPOs its does not show any dependence on the energy, however this was within the sensitivity and energy range of RXTE/PCA. We propose to investigate the rms-energy spectra of 1 Hz QPOs with the wide energy range and higher sensitivity of Astrosat/LAXPC, we request 10 observations during the hard state of the source in this anticipated ToO. This will lead to the understanding of whether 1 Hz QPOs have origins in the Lenz-Thirring precession as proposed.

Dipping X-ray sources show the prescence of a low frequency QPO which is called the 1 Hz QPO. The properties of this QPO are different than those of other low frequency oscillations detected in X-ray binaries. This QPO is detected with equal amplitude (rms) during bursts, persistent emission and dips. Unlike othe low frequency QPOs its does not show any dependence on the energy, however this was within the sensitivity and energy range of RXTE/PCA. We propose to investigate the rms-energy spectra of 1 Hz QPOs with the wide energy range and higher sensitivity of Astrosat/LAXPC, we request 10 observations during the hard state of the source in this anticipated ToO. This will lead to the understanding of whether 1 Hz QPOs have origins in the Lenz-Thirring precession as proposed.

Very recently, a new class of Be/X-ray binaries has been discovered that are persistent, exhibit low luminosity (L_X~10^{34} ergs/s) and have long spin periods (greater than 100~s). Swift~J045106.8-694803 is one of the brightest (10^{36} ergs/s) among all the sources of this new class. It also exhibits the shortest spin period~(168~s) with a very high spin-up rate of $-5.01\pm0.06$ s/yr, indicating strong magnetic field. Moreover, this source tend to show large contribution of the blackbody component to the total flux above 4~keV. Thus, Swift J045106.8-694803 is an excellent source to investigate the link between the hot thermal excess and its strong magnetic field strength~(10^{14} Gauss). We request 80 ks observation of this source with ASTROSAT. The primary goal is to study the characteristics of the power law component~(hard X-rays) in the presence of strong soft X-rays and to investigate evolution of spin period in this system.

We propose a 40 ks observation of the dipping neutron star (NS) low-mass X-ray binary (LMXB) XB 1254-690 with AstroSat. The important goals of our observation are spectroscopy of the energy dependent intensity dips and measuring the variation of the continuum with orbital period of 3.88 hrs using the high spectral resolution of Soft X-ray Telescope (SXT) and the high timing capability of Large Area X-ray Proportional Counter (LAXPC). We will further probe the X-ray emitting and absorbing components by correlating the various timing and spectral properties with the source states. These timing properties include low frequency dipper QPOs, kHz QPOs and millisecond period brightness oscillations. These will provide the spin frequency of the neutron star in this high inclination source for the first time. We will look for bursts in the data to confirm the candidate burst oscillations at the frequency 95 Hz found in a burst previously.

We propose 6360 sec of FUV and NUV observations of merger galaxy NGC~1316 with Astrosat/UVIT with an objective to investigate star-formation processes and distribution of massive stars in it. Though NGC~1316 has been observed during GALEX survey, due to its low spatial resolution and effective exposure, above topics have not previously been explored in detail. Earlier studies of NGC~1316 showed morphological distribution of hot gas which matches well with that of ionized gas and related optical dust features. Color-index and extinction maps derived for this galaxy reveal an intricate and complex dust morphology at 6-7 kpc. It apparently takes the form of an arc-like pattern extending along north-east direction. The presence of multiphase gas such as dust, warm, cool gas etc. shows active star formation in this galaxy. The proposed NUV and FUV observations with UVIT will provide an unique opportunity to study above properties of this galaxy in detail.

ASTROSAT UVIT observations of star formation efficiency and feedback signatures in some of the most massive spiral galaxies with rotation velocities > 300 km/sec are proposed. These galaxies clearly depart from stellar-mass and baryonic-mass Tully-Fisher relations, indicating a significant shortfall of ``condensed" baryon fraction in them, despite their large mass. The high sensitivity of UVIT and its arcsecond scale resolution will be used to investigate their puzzling nature.

ASTROSAT UVIT observations of star formation efficiency and feedback signatures in some of the most massive spiral galaxies with rotation velocities > 300 km/sec are proposed. These galaxies clearly depart from stellar-mass and baryonic-mass Tully-Fisher relations, indicating a significant shortfall of ``condensed" baryon fraction in them, despite their large mass. The high sensitivity of UVIT and its arcsecond scale resolution will be used to investigate their puzzling nature.

ASTROSAT UVIT observations of star formation efficiency and feedback signatures in some of the most massive spiral galaxies with rotation velocities > 300 km/sec are proposed. These galaxies clearly depart from stellar-mass and baryonic-mass Tully-Fisher relations, indicating a significant shortfall of ``condensed" baryon fraction in them, despite their large mass. The high sensitivity of UVIT and its arcsecond scale resolution will be used to investigate their puzzling nature.

We request 50 ks AstroSat observations for the obscured and bright AGN NGC~424. The AGN have well known masses, however, its nature of being Compton thick is still a matter of debate -- whether this AGN has obscuring broad line region or torus like material. The spectroscopy of the AGN show Compton thick absorbers with high covering factors. While the lightcurves exhibit variabilities on minutes to hours timescale indicating less covering factors. This AGN is also known to be very bright though little is known about the values of high energy cutoff. High sensitivity and unprecedented hard X-ray effective area of detectors onboard AstroSat provide the best opportunity to constrain the shape of the continnum and high energy cutoff. Using data from Astrosat, broadband X-ray analysis will allow us to constrain the BLR/torus covering factor and a self consistent spectral-timing picture of the AGN.

We propose a 50 ks observation of a nearby Narrow line Seyfert1 galaxy TON~S180 ($z~\sim0.0062$) to study some of the outstanding problems of AGN phenomenon using Astrosat''s simultaneous multiwavelength capability with UVIT as a primary instrument. Some of these problems include the origin of soft X--ray excess and the optical/UV emission and connection between them, nature of accretion disks, connection between optical/UV. We intend to construct the broadband spectral energy distribution to disentangle between various models that fit statistically equally well. The time delay study will lead to test the models for both the accretion disk and soft excess. The relationship between optical/UV and absorption-free hard X-ray emission above 10~keV will allow us to test thermal Comptonisation models with seeds as optical/UV disk photons.

This proposal is continuation of efforts to obtain the most significant measurement of hard X-ray polarization as function of pulse-phase for the Crab pulsar with AstroSat:CZT-Imager. Pulse phase-resolved polarization measurements of Crab will be helpful in constraining the pulsar emission models and geometry. We have obtained statistically significant polarization measurement for Crab from the available CZTI data in the last 1.5 years(exposure~800ks) when averaged over all phases. These observations also have provided very interesting results for the polarization of pulsed emission as function of pulse-phase, which can provide insights to the pulsar emission models. However the statistical significance of these results are rather low and inorder to make concrete interpretation of these results it is necessary to have much larger exposure time (~2-5Ms). As the requirement of this large exposure time can not be met in a single observation cycle, we propose 500 ks observation of Crab in this cycle.

Nuclear activity and star formation(SF) in galaxies are observed to exist together across redshifts. Nuclear activity can have an impact on the SF properties of the hosts of active galactic nuclei (AGN) via feedback processes. Observationally there are evidences for positive and negative feedback and it is likely that they co-exist. Systematic investigation of the SF properties of AGN hosts on various physical scales (parsec to kilo-parsec) will allow one to (i) reconcile the two contrasting observations on the feedback processes operating on AGN hosts and (ii) examine the complex interplay between black hole activity and SF in AGN. We therefore propose to carry out a systematic analysis of the SF properties of a sample of AGN on physical scales of hundreds of parsecs down to the lowest physical extent allowable by the resolution of UVIT. We request for a total of 43 ksec to observe four AGN.

Nuclear activity and star formation(SF) in galaxies are observed to exist together across redshifts. Nuclear activity can have an impact on the SF properties of the hosts of active galactic nuclei (AGN) via feedback processes. Observationally there are evidences for positive and negative feedback and it is likely that they co-exist. Systematic investigation of the SF properties of AGN hosts on various physical scales (parsec to kilo-parsec) will allow one to (i) reconcile the two contrasting observations on the feedback processes operating on AGN hosts and (ii) examine the complex interplay between black hole activity and SF in AGN. We therefore propose to carry out a systematic analysis of the SF properties of a sample of AGN on physical scales of hundreds of parsecs down to the lowest physical extent allowable by the resolution of UVIT. We request for a total of 43 ksec to observe four AGN.

Nuclear activity and star formation(SF) in galaxies are observed to exist together across redshifts. Nuclear activity can have an impact on the SF properties of the hosts of active galactic nuclei (AGN) via feedback processes. Observationally there are evidences for positive and negative feedback and it is likely that they co-exist. Systematic investigation of the SF properties of AGN hosts on various physical scales (parsec to kilo-parsec) will allow one to (i) reconcile the two contrasting observations on the feedback processes operating on AGN hosts and (ii) examine the complex interplay between black hole activity and SF in AGN. We therefore propose to carry out a systematic analysis of the SF properties of a sample of AGN on physical scales of hundreds of parsecs down to the lowest physical extent allowable by the resolution of UVIT. We request for a total of 43 ksec to observe four AGN.

In recent years, the study of the correlated X-ray/OIR fast variability in black-hole transients (BHTs) is showing more and more promising results. GRS 1915+105 was one of the first BHTs to be studied with a multi-wavelength approach, showing the first strong evidences for a disk-jet connection. As of today, only few X- ray-OIR simultaneous observations have been reported of this source. We therefore propose to participate with ASTROSAT to an already approved multi-wavelength observing campaign to study the X-ray-IR fast variability, together with XMM-Newton and VLT, in order to cover the hard X-ray band. ASTROSAT sensibility in the hard X-rays will be crucial to study the inflow-outflow connection, avoiding he accretion disc contamination.

We propose to study the accretion rates of PDS 11 and LDS 5606, which belong to the rare class of nearby, isolated T Tauri stars. These stars belong to wide binary systems with separations greater than 1 kau. PDS 11 and LDS 5606 are the only wide binaries in the Galaxy where both the components host active accretion discs. The age of these classical T Tauri stars are older than 10 Myr. It has been considered that the disc in young stellar objects like PDS11 get disrupted over a period of 6 Myr. Accretion rates estimated from UV excess are considered more precise compared to Ha. We propose to estimate UV excess from observations using UVIT to confirm whether the binary companions of these stars are actively accreting. This will help us to understand the accretion process, and the disc survival in these old T Tauri stars.

We request 35ks observation of the black hole transient Swift J1357.2-0933. We will like that the source be observed with LAXPC, SXT, CZTI and UVIT particularly during outburst. The present proposal is meant to corroborate ongoing attempt to understand the origin of the peculiar behaviour observed in this black hole transient. More so, this source is of particular interest because it is a high galactic latitude source which will enable simultaneous observation with the multi-wavelength capability of AstroSat. We will like to probe the toroidal environment of this source using the multi-wavelength capability of AstroSat. This will provide vital information about the geometry of the regions in the immediate vicinity of the black hole. Until now, it is unclear where the obscuring torus in this system is located and how it affects the observed emission from this black hole candidate both on the disc and in the corona.

We propose a 40~ksec observation of SAX~J2103.5+4545 with Astrosat. The X-ray pulsations in this system is detected even at $L_{x}\sim10^{33}~erg~s^{-1}$, the lowest luminosity ever reached by an accreting pulsar with pulsed emission in quiescence. At outburst peaks, the X-ray luminosity reaches $(0.6 - 1.0) \times10^{37}~erg~s^{-1}$. In past, the pulsar had shown phases of rapid spin-up/spin-down during outbursts. From the rapid spin-up of the pulsar, an indirect estimation of magnetic field $\sim10^{12}$~G implies a cyclotron line near 10-20~keV. However, such features were not found from previous observations. The broad-band coverage of Astrosat would help us in direct estimation of magnetic field in the pulsar for first time with detection of cyclotron lines in the spectra. The X-ray spectral and timing studies of the pulsar would allow us to study the spectral variability and will be useful in estimating spin period of the pulsar in present epoch.

We propose an anticipated ToO to perform the detailed study of a representative sample of three blazars spread across different sub-classes. The proposed study aims to constrain the particle energy distribution (PED) of energizing leptons responsible for the blazars outbursts. We request for 120 ks, 140 ks and 140 ks observations for PKS 2155-304, S5 0716+714 and 3C 454.3, respectively, triggered by increasing Fermi count rates. This shall be part of a multiwavelength campaign including many modern space and ground based facilities covering a large range in frequencies. AstroSat, because of its simultaneous broadband coverage, shall uniquely contribute to constraining spectral curvatures in the multiwavelength SED

We propose an anticipated ToO to perform the detailed study of a representative sample of three blazars spread across different sub-classes. The proposed study aims to constrain the particle energy distribution (PED) of energizing leptons responsible for the blazars outbursts. We request for 120 ks, 140 ks and 140 ks observations for PKS 2155-304, S5 0716+714 and 3C 454.3, respectively, triggered by increasing Fermi count rates. This shall be part of a multiwavelength campaign including many modern space and ground based facilities covering a large range in frequencies. AstroSat, because of its simultaneous broadband coverage, shall uniquely contribute to constraining spectral curvatures in the multiwavelength SED

We propose to image the biconical Red Rectangle Nebula around HD 44179 in the NUV and FUV with selected UVIT NUV and FUV filters. We also propose to obtain NUV and FUV grating spectra of this target. The science objective is to image the nebular environment around HD~44179 in the ultraviolet for the first time. The Red Rectangle is the strongest known source of Extended Red Emission (ERE); the ERE forms a continuous spectrum from 5500---8500 A, with sharper features reminiscent of molecular bands superimposed. The FUV spectrum of HD 44179 is dominated by strong absorption from the 4th Positive bands of the CO molecule. HD 44179 is the only known extrasolar source of CO Cameron band emission (2000---2200 A). We propose to image the Red Rectangle Nebula in the UV to determine whether this CO emission is spatially coincident with the biconical Red Rectangle Nebula in the red.

SMC X-1 is a peculiar neutron star HMXB which defy typical behaviour of other HMXBs. At odds with other HMXBs, it shows steady spin-up. It also exhibits Type II bursts, probably caused by the viscous instability of an accretion disk and the soft versus hard X-ray pulse profiles of SMC X-1 are offset, probably because of different origin. It’s Suzaku spectrum hint a CRSF at ~ 40 keV during high flux states along with pulsating soft excess which is but not confirmed in Nustar data. We propose 60 ks observation with LAXPC, SXT and CZTI in the high intensity state for indepth timing and deep hardness-ratio resolved analysis of SMC X-1 which will allow us to understand the origin of these flares more closely along with characterizing the broadband X-ray spectrum and probing the possible presence of the CRSF feature.

How interstellar dust attenuates starlight with wavelength is critical and fundamental to our understanding of galaxies. In the ultraviolet, the Milky Way dust attenuation shows a bump, while other attenuation relations does not. We ask for ultraviolet observations of 5 overlapping galaxy pairs. Modeling both galaxies, one can estimate the amount of background galaxy flux attenuated by the dust in the foreground disk galaxy. Together with optical and near-infrared data, the dust attenuation as a function of wavelength is directly measured. Two UV filter observations map the bump in the attenuation relation for the first time in other galaxies and ULX observations concurrently, to estimate nuclear source activity for galaxy pairs that are explicitly not interacting. We will fit the dominant attenuation relation and any relations between the attenuation-wavelength relation and the mass, type, position, and star-formation of the foreground disks.

How interstellar dust attenuates starlight with wavelength is critical and fundamental to our understanding of galaxies. In the ultraviolet, the Milky Way dust attenuation shows a bump, while other attenuation relations does not. We ask for ultraviolet observations of 5 overlapping galaxy pairs. Modeling both galaxies, one can estimate the amount of background galaxy flux attenuated by the dust in the foreground disk galaxy. Together with optical and near-infrared data, the dust attenuation as a function of wavelength is directly measured. Two UV filter observations map the bump in the attenuation relation for the first time in other galaxies and ULX observations concurrently, to estimate nuclear source activity for galaxy pairs that are explicitly not interacting. We will fit the dominant attenuation relation and any relations between the attenuation-wavelength relation and the mass, type, position, and star-formation of the foreground disks.

How interstellar dust attenuates starlight with wavelength is critical and fundamental to our understanding of galaxies. In the ultraviolet, the Milky Way dust attenuation shows a bump, while other attenuation relations does not. We ask for ultraviolet observations of 5 overlapping galaxy pairs. Modeling both galaxies, one can estimate the amount of background galaxy flux attenuated by the dust in the foreground disk galaxy. Together with optical and near-infrared data, the dust attenuation as a function of wavelength is directly measured. Two UV filter observations map the bump in the attenuation relation for the first time in other galaxies and ULX observations concurrently, to estimate nuclear source activity for galaxy pairs that are explicitly not interacting. We will fit the dominant attenuation relation and any relations between the attenuation-wavelength relation and the mass, type, position, and star-formation of the foreground disks.

How interstellar dust attenuates starlight with wavelength is critical and fundamental to our understanding of galaxies. In the ultraviolet, the Milky Way dust attenuation shows a bump, while other attenuation relations does not. We ask for ultraviolet observations of 5 overlapping galaxy pairs. Modeling both galaxies, one can estimate the amount of background galaxy flux attenuated by the dust in the foreground disk galaxy. Together with optical and near-infrared data, the dust attenuation as a function of wavelength is directly measured. Two UV filter observations map the bump in the attenuation relation for the first time in other galaxies and ULX observations concurrently, to estimate nuclear source activity for galaxy pairs that are explicitly not interacting. We will fit the dominant attenuation relation and any relations between the attenuation-wavelength relation and the mass, type, position, and star-formation of the foreground disks.

In order to understand the instrument background and to develop the robust background model for the same, we need frequent background observations which cover complete range of latitude and longitude which corresponds to about one day observation. Blank sky (background) observation are essential if we want any meaningful science from AstroSat/LAXPC data with source strength below 50% of the LAXPC background. More than 50% of all AstroSat observations will have signal strength below this level and hence understanding LAXPC background is very important if we want any meaningful science from these observed faint sources.

BL Lac object OJ287 is the most promising candidate for the existence of a supermassive black hole binary inspiralling under the action of gravitational wave emission. The Event Horizon Telescope (EHT) consortium is trying to image and if possible resolve the binary Black Hole central engine of OJ287 and April 2017 AstroSat observations were part of EHT''''''''s new campaign on OJ287. Another EHT campaign is expected to happen during the spring of 2018. We propose a single AstroSat pointing of 120 ks on OJ287 during this campaign. The deep observations by AstroSat will help us in constraining the valley part of SED of OJ287 and also to explore its central engine. These combined MW observations are expected to clarify the origin of a possible precessing helical jet in OJ287 . This proposal is for an anticipated ToO, to be triggered by the planned EHT + ALMA observations.

Long tidal tails and bridges are typically produced in minor mergers or flyby binary galaxy interactions, as major mergers are relatively uncommon in the local universe. These tails and bridges are active sites of star formation - leading to young star-formation complexes (SFC), even tidal dwarf galaxies (TDG). How and when these objects are formed remain to be explored in a systematic fashion. So are their physical nature. We propose to investigate three interacting galaxy system, Arp 305, NGC 2782 and Arp 105 using deep UVIT imaging observation in two NUV and one FUV broadband filters. The resulting colors, in addition to the UV-optical, infrared colors, will be used to characterize the size, mass and physical nature of the SFCs and possible candidate TDGs. With UVIT''s better PSF and sensitivity, we will derive the number statistics, distribution of these SFCs and morphology, age and metallicity of the TDGs.

Long tidal tails and bridges are typically produced in minor mergers or flyby binary galaxy interactions, as major mergers are relatively uncommon in the local universe. These tails and bridges are active sites of star formation - leading to young star-formation complexes (SFC), even tidal dwarf galaxies (TDG). How and when these objects are formed remain to be explored in a systematic fashion. So are their physical nature. We propose to investigate three interacting galaxy system, Arp 305, NGC 2782 and Arp 105 using deep UVIT imaging observation in two NUV and one FUV broadband filters. The resulting colors, in addition to the UV-optical, infrared colors, will be used to characterize the size, mass and physical nature of the SFCs and possible candidate TDGs. With UVIT''s better PSF and sensitivity, we will derive the number statistics, distribution of these SFCs and morphology, age and metallicity of the TDGs.

n order to understand the instrument background and to develop the robust background model for the same, we need frequent background observations which cover complete range of latitude and longitude which corresponds to about one day observation. Blank sky (background) observation are essential if we want any meaningful science from AstroSat/LAXPC data with source strength below 50% of the LAXPC background. More than 50% of all AstroSat observations will have signal strength below this level and hence understanding LAXPC background is very important if we want any meaningful science from these observed faint sources.

We request two 20 ksec observations of the Neutron Star Low Mass X-Ray Binary (LMXB) MXB 1730-335 (the ‘Rapid Burster’) during its next outburst. In previous outbursts, the Rapid Burster has displayed complex ‘classes’ of variability previously only seen in the Black Hole LMXBs GRS 1915+105 and IGR J17091-3624. Only 2 classes have been observed in the Rapid Burster, compared to 15 and 9 respectively in GRS 1915+105 and IGR J17091-3624. With LAXPC and SXT we aim to observe and perform phaseresolved spectroscopy of additional classes in the lightcurve of the Rapid Burster, and the presence or absence of these classes will allow us to quantify the role of the compact object in GRS 1915-like variability. We also expect to observe ~100 Type I and II X-Ray Bursts, allowing us to further burst population studies performed by previous authors.

IGR J17091-3624 is an LMXB that displays a complex set of 'variability classes' in its X-ray flux over time. Similar behaviour seen in GRS 1915+105 was thought to be driven by near-Eddington-limit accretion. Recent suggestions that IGR J17091-3624 accretes far below Eddington have cast doubt on this interpretation. GRS 1915+105 has been in outburst since discovery; studies of IGR J17091 present us with the only opportunity to study the evolution of outbursts containing GRS 1915-like variability. This helps us to understand how these objects differ from the many LMXBs which do not show this variability. We propose a series of AstroSat observations to study the next outburst of this source, consisting of 5 observations of 6\,ksec each over 250 days, to study the GRS 1915-like variability in the context of the wider outburst and to increase the number of observations of variability classes in IGR J17091.

The objective of this project is to characterize with unprecedented accuracy the star-forming regions of one of the best studied nearby spiral galaxies, NGC 628, by combining two highly complementary tools: imaging spectroscopy in the visible of the ionized gas using SITELLE (data in hand) and ultraviolet imagery of the underlying ionizing stellar populations using UVIT. A set of UVIT filters is selected (FUV-F2, FUV-F5, NUV-F2, NUV-F3, NUV-F5, and VIS1) to cover sensitive regions over the SED of young stellar clusters. While SITELLE provides, with a spatial resolution similar to UVIT, a measurement of the gas emission lines, the clusters’ parameters will become inputs for a photoionization code used to gather the gas properties. These combined information from the ionized gas and stellar populations will allow us to study the impact of star formation and different mixing mechanisms on the evolution of an isolated spiral galaxy.

We propose to observe a small sample of young T Tauri stars in their classical (accreting) and weak line (non-accreting) stages. At early epochs, UV flux from a T Tauri star is accretion-dominated, and as the disk dissipates only the chromospheric contribution remains. Accretion shocks are believed to generate most of the energy in the UV, with a characteristic shock temperature of $\sim$ 10$^4$ K, but this has yet not been firmly established. The evolution of the UV spectrum is moreover unknown, despite the importance of UV in heating the disk gas, influencing gas chemistry and driving photo evaporative winds. From multi-band UVIT observations of young stars with varying mass accretion rates, we will determine the link between the FUV and NUV emission---these observations will form a first step toward characterizing the FUV continuum.

We propose to observe a small sample of young T Tauri stars in their classical (accreting) and weak line (non-accreting) stages. At early epochs, UV flux from a T Tauri star is accretion-dominated, and as the disk dissipates only the chromospheric contribution remains. Accretion shocks are believed to generate most of the energy in the UV, with a characteristic shock temperature of $\sim$ 10$^4$ K, but this has yet not been firmly established. The evolution of the UV spectrum is moreover unknown, despite the importance of UV in heating the disk gas, influencing gas chemistry and driving photo evaporative winds. From multi-band UVIT observations of young stars with varying mass accretion rates, we will determine the link between the FUV and NUV emission---these observations will form a first step toward characterizing the FUV continuum.

We propose to observe a small sample of young T Tauri stars in their classical (accreting) and weak line (non-accreting) stages. At early epochs, UV flux from a T Tauri star is accretion-dominated, and as the disk dissipates only the chromospheric contribution remains. Accretion shocks are believed to generate most of the energy in the UV, with a characteristic shock temperature of $\sim$ 10$^4$ K, but this has yet not been firmly established. The evolution of the UV spectrum is moreover unknown, despite the importance of UV in heating the disk gas, influencing gas chemistry and driving photo evaporative winds. From multi-band UVIT observations of young stars with varying mass accretion rates, we will determine the link between the FUV and NUV emission---these observations will form a first step toward characterizing the FUV continuum.

We propose to observe a small sample of young T Tauri stars in their classical (accreting) and weak line (non-accreting) stages. At early epochs, UV flux from a T Tauri star is accretion-dominated, and as the disk dissipates only the chromospheric contribution remains. Accretion shocks are believed to generate most of the energy in the UV, with a characteristic shock temperature of $\sim$ 10$^4$ K, but this has yet not been firmly established. The evolution of the UV spectrum is moreover unknown, despite the importance of UV in heating the disk gas, influencing gas chemistry and driving photo evaporative winds. From multi-band UVIT observations of young stars with varying mass accretion rates, we will determine the link between the FUV and NUV emission---these observations will form a first step toward characterizing the FUV continuum.

Observations: We request 14700 seconds of UV observations of three blue compact dwarf (BCD) galaxies: VII Zw 403, NGC 3738, and Haro 36. Context: BCDs are undergoing a burst of star formation. It has yet to be observationally confirmed what triggers this burst of star formation for BCDs. Atomic hydrogen studies have revealed several potential starburst triggers in our proposed sample: gas accretion, dwarf-dwarf mergers, and ram- pressure stripping. Objectives/Results: We will use UVIT to look for features that may distinguish different starburst triggers. In galaxy mergers with remnant tidal features, we expect to see young stars that have been expelled from the disk into tidal tails. For ram-pressure stripping, we expect to see young stars in gas that has been stripped from the galaxy. Intergalactic medium being accreted onto a galaxy would be expected to have no measurable emission from new stars.

Observations: We request 14700 seconds of UV observations of three blue compact dwarf (BCD) galaxies: VII Zw 403, NGC 3738, and Haro 36. Context: BCDs are undergoing a burst of star formation. It has yet to be observationally confirmed what triggers this burst of star formation for BCDs. Atomic hydrogen studies have revealed several potential starburst triggers in our proposed sample: gas accretion, dwarf-dwarf mergers, and ram- pressure stripping. Objectives/Results: We will use UVIT to look for features that may distinguish different starburst triggers. In galaxy mergers with remnant tidal features, we expect to see young stars that have been expelled from the disk into tidal tails. For ram-pressure stripping, we expect to see young stars in gas that has been stripped from the galaxy. Intergalactic medium being accreted onto a galaxy would be expected to have no measurable emission from new stars.

Observations: We request 14700 seconds of UV observations of three blue compact dwarf (BCD) galaxies: VII Zw 403, NGC 3738, and Haro 36. Context: BCDs are undergoing a burst of star formation. It has yet to be observationally confirmed what triggers this burst of star formation for BCDs. Atomic hydrogen studies have revealed several potential starburst triggers in our proposed sample: gas accretion, dwarf-dwarf mergers, and ram- pressure stripping. Objectives/Results: We will use UVIT to look for features that may distinguish different starburst triggers. In galaxy mergers with remnant tidal features, we expect to see young stars that have been expelled from the disk into tidal tails. For ram-pressure stripping, we expect to see young stars in gas that has been stripped from the galaxy. Intergalactic medium being accreted onto a galaxy would be expected to have no measurable emission from new stars.

We propose a 85~ks observation of Cen~X-3 with Astrosat covering entire binary orbit. Though earlier observations were carried out during eclipse and high intensity phases, there exists only one Suzaku observation covering nearly entire orbit. During this observation, several low intensity phases/dips are seen in light curves of the pulsar. Presence of additional dense matter (clumps) at dip phases has been reported from this observation. Model calculations showed that, dips at late orbital phases appear due to the presence of accretion wake. However lack of observations at late orbital phases did not help in investigating the cause of such dips. Considering this, we propose to observe Cen~X-3 with Astrosat to carry out detailed investigation of the cause of these dips - whether associated with the geometry of the binary, accretion wakes, presence of clumps, properties of the source during high and low intensity phases, cyclotron line features at different luminosities.

We request multi-wavelength observations of Swift/BAT-selected, hard X-ray bright sample of 4 type 1 active galactic nuclei. Using AstroSat and ground-based optical telescopes, we plan to derive simultaneous multi-wavelength spectral energy distributions, including the far and near UV grating spectra, of AGN for the first time. We will use these data, and (i) derive bolometric luminosity, accretion rate and bolometric correction factor, (ii) probe range of spectral complexity in type 1 AGN, (iii) test accretion disk models, (iv) study connection between the disk emission and the shape of X-ray continua, (v) investigate any connection between the disk reflection and the thermal emission from the disk.

We request multi-wavelength observations of Swift/BAT-selected, hard X-ray bright sample of 4 type 1 active galactic nuclei. Using AstroSat and ground-based optical telescopes, we plan to derive simultaneous multi-wavelength spectral energy distributions, including the far and near UV grating spectra, of AGN for the first time. We will use these data, and (i) derive bolometric luminosity, accretion rate and bolometric correction factor, (ii) probe range of spectral complexity in type 1 AGN, (iii) test accretion disk models, (iv) study connection between the disk emission and the shape of X-ray continua, (v) investigate any connection between the disk reflection and the thermal emission from the disk.

We request multi-wavelength observations of Swift/BAT-selected, hard X-ray bright sample of 4 type 1 active galactic nuclei. Using AstroSat and ground-based optical telescopes, we plan to derive simultaneous multi-wavelength spectral energy distributions, including the far and near UV grating spectra, of AGN for the first time. We will use these data, and (i) derive bolometric luminosity, accretion rate and bolometric correction factor, (ii) probe range of spectral complexity in type 1 AGN, (iii) test accretion disk models, (iv) study connection between the disk emission and the shape of X-ray continua, (v) investigate any connection between the disk reflection and the thermal emission from the disk.

We request multi-wavelength observations of Swift/BAT-selected, hard X-ray bright sample of 4 type 1 active galactic nuclei. Using AstroSat and ground-based optical telescopes, we plan to derive simultaneous multi-wavelength spectral energy distributions, including the far and near UV grating spectra, of AGN for the first time. We will use these data, and (i) derive bolometric luminosity, accretion rate and bolometric correction factor, (ii) probe range of spectral complexity in type 1 AGN, (iii) test accretion disk models, (iv) study connection between the disk emission and the shape of X-ray continua, (v) investigate any connection between the disk reflection and the thermal emission from the disk.

Blazars are highly variable astronomical sources having variation time period ranging from few hours, months or even years. One of the Fermi detected blazar 4C +21.35 exhibits strong flare in $\gamma$-rays both very short term ($\sim$ week) and as well as extremely longer period (few years). From the analysis of nearly eight years of observations from Fermi satellite we found that the average $\gamma$-ray flux of the source rises steadily for $\sim 1$ year and then decays for more than a year to low $\gamma$-ray activity state. To understand the radiative process in this source during high or low $\gamma$-ray activity state, we propose simultaneous observation of 4C +21.35 with UVIT, SXT along with LAXPC and CZTI detectors on board ASTROSAT satellite to construct the broadband spectra of the source and to better understand the physical process responsible for such variations in the $\gamma$-ray activity state.

We propose to acquire 2.4 ks Ultra-Violet (UV) imagery of one of the famous near-by starburst superwind galaxy MESSIER 082 (M 82) with the currently available highest spatial resolution UVIT telescope of ASTROSAT. Main objective of the proposed observations is to study the origin of young stellar population, dust and interstellar gas properties and star formation processes independent of the optical band. Also our aim is to understand the evolution of galaxy using UV observations. This starburst galaxy has been detected in nearly all wavelength ranging from radio, optical-to-GeV. This suggest that interstellar medium of M 82 galaxy exists in all the possible phases. Past studies employing optical and X-ray observations have detected Ultra-luminous sources (ULXs) and Supernovae (SNe). Therefore, the proposed NUV and FUV observations with Ultraviolet Imaging Telescope (UVIT) (along with SXT) will provide an unique opportunity to study above properties of this galaxy in detail.

Low mass neutron star X-ray binaries are known to have soft and hard X-ray spectral states like blackhole binaries. They also show a sudden rise in X-ray intensity (type-I thermonuclear burst) due to the unstable burning of matter accumulated on the neutron star surface. We propose a 50 ks observation of one of the poorly studied neutron star buster 4U 1812-12 with Astrosat. The aim of this proposal is to study the photospheric radius expansion during bursts for constraining the neutron star radii using high sensitivity instruments on-board Astrosat. Study of spectral and timing properties will be essential for understanding the changes in spectral state, spin period, neutron star and accretion disk interaction and origin of high energy emissions from these source. Investigation of these properties mainly relies on the unique broadband and timing capabilities of Astrosat that will advance the knowledge of accretion processes in low accretion rate regime.

We propose here ASTROSAT observations of 13 blazars, for a total of 235 ksec on source, to complete the broad-band X-rays follow-up of a well-defined radio selected sample of High-Energy peaked BL Lacs, all but one detected by FERMI and important TeV-emitters: out of the 13 proposed targets, 10 have been already observed at TeV energy, with 9 detection and 1 non-detection. The ASTROSAT sensitivity above 10 keV offers us the possibility to firmly constrain the descending part of the synchrotron emission. This spectral feature is critical to determine the maximum energy of the population of electrons responsible for the observed broad-band emission and, therefore, to derive the jet power and to constrain the acceleration mechanisms.

We propose here ASTROSAT observations of 13 blazars, for a total of 235 ksec on source, to complete the broad-band X-rays follow-up of a well-defined radio selected sample of High-Energy peaked BL Lacs, all but one detected by FERMI and important TeV-emitters: out of the 13 proposed targets, 10 have been already observed at TeV energy, with 9 detection and 1 non-detection. The ASTROSAT sensitivity above 10 keV offers us the possibility to firmly constrain the descending part of the synchrotron emission. This spectral feature is critical to determine the maximum energy of the population of electrons responsible for the observed broad-band emission and, therefore, to derive the jet power and to constrain the acceleration mechanisms.

The source 4U 1702-429 is a Low Mass X-ray Binary system, whose broadband spectrum is not well studied yet. We propose to observe the source for the first time with AstroSat, for a duration of 60ks. Our primary science goal is to investigate the connection between the relativistic Fe lines and the kHz QPO, both of which are expected to originate near the neutron star. Our secondary goal would be the study of the specto-temporal features of the thermonuclear bursts and oscillations (if detected). LAXPC will be the primary instrument for observations. However, since our science objectives are well within the capabilities of AstroSat, and is best achieved with a multi-wavelength study, we will also require simultaneous SXT and CZTI observations. This study upon completion, has the potential to bring in significant advancement in this field.

We request 30 ks {\it AstroSat/UVIT} observation of a narrow line Seyfert~1 galaxy MRK~359 exhibiting strong soft X-ray excess. The origin of soft X-ray excess has been one of the extraordinary problem in the field of AGN. Also, this AGN has shown remarkable variability in Optical/UV and X-ray emission on few minutes to month timescales. Due to lack of simultaneous coverage from Optical/UV and X-ray bands from existing missions/observatories, it is difficult for a detailed investigation on the origin of soft X-ray excess and the observed variability in different bands. {\it AstroSat's} unprecedented multiwavelength capability can play a major role due to its high effective area of LAXPC in hard band and simultaneous UV/Optical observations from UVIT. Along with SXT and CZTI, we will be able to address the origin of soft excess and its connection to soft photons from the accretion disk and hard X-rays from hot X-ray corona.

A prototypical low mass X-ray binary (LMXB) 1E 1740.7-2942 is located 50 arcmin apart from the Galactic Center, is the hardest X-ray source in this region. The X-ray states of the source are strongly resemble to Cyg X-1. The bipolar radio jets of 1E 1740.7-2942 are very reminiscent of a radio galaxy. The true nature of the object has thus remained an open question for nearly a quarter of a century. We propose 50 ks observation of 1E 1740.7-2942 with AstroSat to study the nature of sustained low hard state in this source and possibly find signature of any connection of disk accretion with the precessing Radio jet. With the excellent timing capability of Large Area X-ray Proportional Counter (LAXPC) we will search for possible quasi-periodic oscillations (QPOs) and study timing properties of the source.

We request two 40 ks (total 80 ks) ASTROSAT observation (~ 6 months apart) of Her X-1 with LAXPC (prime), SXT and CZTI to study the characteristics of the cyclotron line in its X-ray spectrum. In Her X-1 a long-term decay of cyclotron line energy Ecyc has been found during the period 1995-2004. But recently in August 2016, an upward trend has been noticed. A similar upward jump occurred during 1990-1993, but no observation was done to cover this earlier episode. We are now presented with an excellent opportunity to track this upward trend by continuously monitoring the object using several current satellites. Time has already been granted by NuSTAR for two observations (half a year apart), and the corresponding proposal has been submitted for INTEGRAL. We propose ASTROSAT observations as a part of this multi-mission monitoring programme for the cyclotron line in Her X-1.

??? 1012 G)has shown a long term spin variation ?les are strongly depends on energy. The source undergo into two periodic X-ray outburst in one orbital phase, during its periastron and aphelion passage.The periodic X-ray outbursts are dependent on both the binary motion and the size of the circumsteller disc. ?erent spectral properties. The hard spectrum is relatively weak and even disappear in the low energies <3 keV where as the second peak has very soft spectrum and cannot be observed above 5 keV. Soft spectrum needs further studies with soft X-ray Telescope. We are proposing 60 ks explosure with ASTROSAT during its outburst phase.

Groups contain most of the galaxies in the Local Universe and are the site of profound galaxy morphological and SF transformations. Dorado, a non virialized, HI rich, nearby association, offers the unique opportunity to investigate a way station towards a more relaxed stage. The recession velocity distribution of its members marks three linked clumps where early-types show past interaction signatures and FUV bright rings/arm-like structures. We ask for a UVIT mini-survey imaging 10 fields in the F148W and N242W filters covering the Dorado backbone to perform galaxy surface photometry down to $\mu_{N242W}\approx$28.5-29 mag arcsec$^{-2}$ unveiling UV galaxy structures. UVIT "ground-based" optical imaging PSF and its 28'' [FoV] diameter will allow the investigation of galactic and extragalactic SF regions, also along HI tails created by interaction. Combined with our deep imaging at ESO-VST covering the entire Dorado group, UVIT will complete our understanding of SF and dissipative processes evolution in groups.

Groups contain most of the galaxies in the Local Universe and are the site of profound galaxy morphological and SF transformations. Dorado, a non virialized, HI rich, nearby association, offers the unique opportunity to investigate a way station towards a more relaxed stage. The recession velocity distribution of its members marks three linked clumps where early-types show past interaction signatures and FUV bright rings/arm-like structures. We ask for a UVIT mini-survey imaging 10 fields in the F148W and N242W filters covering the Dorado backbone to perform galaxy surface photometry down to $\mu_{N242W}\approx$28.5-29 mag arcsec$^{-2}$ unveiling UV galaxy structures. UVIT "ground-based" optical imaging PSF and its 28'' [FoV] diameter will allow the investigation of galactic and extragalactic SF regions, also along HI tails created by interaction. Combined with our deep imaging at ESO-VST covering the entire Dorado group, UVIT will complete our understanding of SF and dissipative processes evolution in groups.

Groups contain most of the galaxies in the Local Universe and are the site of profound galaxy morphological and SF transformations. Dorado, a non virialized, HI rich, nearby association, offers the unique opportunity to investigate a way station towards a more relaxed stage. The recession velocity distribution of its members marks three linked clumps where early-types show past interaction signatures and FUV bright rings/arm-like structures. We ask for a UVIT mini-survey imaging 10 fields in the F148W and N242W filters covering the Dorado backbone to perform galaxy surface photometry down to $\mu_{N242W}\approx$28.5-29 mag arcsec$^{-2}$ unveiling UV galaxy structures. UVIT "ground-based" optical imaging PSF and its 28'' [FoV] diameter will allow the investigation of galactic and extragalactic SF regions, also along HI tails created by interaction. Combined with our deep imaging at ESO-VST covering the entire Dorado group, UVIT will complete our understanding of SF and dissipative processes evolution in groups.

The neutron star SAX J1808.4-3658 (hereafter J1808) was the first discovered accreting millisecond period X-ray pulsar (AMXP). J1808 is a Rosetta Stone system showing the evolutionary role of accretion in spinning neutron stars up to millisecond (ms) spin periods in low mass X-ray binaries (LMXBs) to form ms radio pulsars. The observed X-ray pulsations originate from the neutron star&#39;&#39;s surface, allowing pulse-shape analyses to determine the star&#39;&#39;s mass and radius, which could allow the equation of state of ultra-dense nuclear matter to be constrained. The pulsations are only visible when the AMXP is in a bright state (outburst). We propose to observe J1808 for 40ks during its next outburst, allowing us to measure its spectrum and pulse shapes. These will be used to determine the neutron star&#39;&#39;s mass, radius, and orbital period changes, leading to better understanding of the properties of neutron stars and accretion in LMXBs.

M31 is the nearest giant spiral galaxy for which we can study the supernova remnants, X-ray sources, and stellar populations. At a distance of 780 kpc, M31 is far enough away that the brightest stars are safe to observe with UVIT, yet close enough to obtain a good census of the supernova remnants, X-ray sources, and hot stellar populations. The high spatial resolution of UVIT will yield outstanding data on the stellar populations of M31. The spatial resolution of SXT is sufficient to resolve the X-ray source populations which includes measuring the supernova remnant population. The resulting multi-wavelength images of M31 will form a legacy dataset to be used for study of the stellar populations of M31, it star formation history and the structure of the galaxy.

M31 is the nearest giant spiral galaxy for which we can study the supernova remnants, X-ray sources, and stellar populations. At a distance of 780 kpc, M31 is far enough away that the brightest stars are safe to observe with UVIT, yet close enough to obtain a good census of the supernova remnants, X-ray sources, and hot stellar populations. The high spatial resolution of UVIT will yield outstanding data on the stellar populations of M31. The spatial resolution of SXT is sufficient to resolve the X-ray source populations which includes measuring the supernova remnant population. The resulting multi-wavelength images of M31 will form a legacy dataset to be used for study of the stellar populations of M31, it star formation history and the structure of the galaxy.

M31 is the nearest giant spiral galaxy for which we can study the supernova remnants, X-ray sources, and stellar populations. At a distance of 780 kpc, M31 is far enough away that the brightest stars are safe to observe with UVIT, yet close enough to obtain a good census of the supernova remnants, X-ray sources, and hot stellar populations. The high spatial resolution of UVIT will yield outstanding data on the stellar populations of M31. The spatial resolution of SXT is sufficient to resolve the X-ray source populations which includes measuring the supernova remnant population. The resulting multi-wavelength images of M31 will form a legacy dataset to be used for study of the stellar populations of M31, it star formation history and the structure of the galaxy.

M31 is the nearest giant spiral galaxy for which we can study the supernova remnants, X-ray sources, and stellar populations. At a distance of 780 kpc, M31 is far enough away that the brightest stars are safe to observe with UVIT, yet close enough to obtain a good census of the supernova remnants, X-ray sources, and hot stellar populations. The high spatial resolution of UVIT will yield outstanding data on the stellar populations of M31. The spatial resolution of SXT is sufficient to resolve the X-ray source populations which includes measuring the supernova remnant population. The resulting multi-wavelength images of M31 will form a legacy dataset to be used for study of the stellar populations of M31, it star formation history and the structure of the galaxy.

M31 is the nearest giant spiral galaxy for which we can study the supernova remnants, X-ray sources, and stellar populations. At a distance of 780 kpc, M31 is far enough away that the brightest stars are safe to observe with UVIT, yet close enough to obtain a good census of the supernova remnants, X-ray sources, and hot stellar populations. The high spatial resolution of UVIT will yield outstanding data on the stellar populations of M31. The spatial resolution of SXT is sufficient to resolve the X-ray source populations which includes measuring the supernova remnant population. The resulting multi-wavelength images of M31 will form a legacy dataset to be used for study of the stellar populations of M31, it star formation history and the structure of the galaxy.

M31 is the nearest giant spiral galaxy for which we can study the supernova remnants, X-ray sources, and stellar populations. At a distance of 780 kpc, M31 is far enough away that the brightest stars are safe to observe with UVIT, yet close enough to obtain a good census of the supernova remnants, X-ray sources, and hot stellar populations. The high spatial resolution of UVIT will yield outstanding data on the stellar populations of M31. The spatial resolution of SXT is sufficient to resolve the X-ray source populations which includes measuring the supernova remnant population. The resulting multi-wavelength images of M31 will form a legacy dataset to be used for study of the stellar populations of M31, it star formation history and the structure of the galaxy.

Draco, an intermediate-velocity, high-galactic latitude cloud located at a distance of ~ 550 pc, is suggested to have formed due to the interaction of galactic halo gas entering the Milky Way disk. Previous studies have detected hot gas in the cloud. Turbulent mixing layers initiated by shear flows at the boundary between hot and cold gases are considered as possible mechanism for producing ultraviolet (UV) emission lines. In this proposal we plan to observe three fields towards Draco cloud in far ultraviolet (FUV) and near-ultraviolet (NUV) wavelengths using combinations of F169M, F172M and N245M, N263M filters to detect C IV $\lambda$1550 doublet (primary objective) and C II] $\lambda$2326 excess emission from the cloud at higher spatial resolution of $2^{\prime}$ . Combining results from this proposed observations and our ground based narrow-band optical imaging would allow us to characterize the turbulent mixing scenario possibly at work in the Draco cloud.

The response of the opt/UV continuum to large amplitude X-ray variability can probe the disc structure in AGN. We request a week long AstroSat observation of the NLS1 Ark~564 accreting at near Eddington rate to obtain lightcurves and time-resolved grating spectra with a sampling rate at a fraction of a day. We will measure the wavelength dependent time-lag using the UVIT gratings/filters and the SXT data. We will also study UV continuum spectral variability with grating spectra on short time scales and probe accretion disk heating by X-ray illumination. We will also perform coordinated observations with optical telescopes. The proposed observations will allow us to probe and study the nature of accretion discs in the high accretion rate regime (ie accretion rate close to the Eddington limit), which has not been achieved before.

The response of the opt/UV continuum to large amplitude X-ray variability can probe the disc structure in AGN. We request a week long AstroSat observation of the NLS1 Ark~564 accreting at near Eddington rate to obtain lightcurves and time-resolved grating spectra with a sampling rate at a fraction of a day. We will measure the wavelength dependent time-lag using the UVIT gratings/filters and the SXT data. We will also study UV continuum spectral variability with grating spectra on short time scales and probe accretion disk heating by X-ray illumination. We will also perform coordinated observations with optical telescopes. The proposed observations will allow us to probe and study the nature of accretion discs in the high accretion rate regime (ie accretion rate close to the Eddington limit), which has not been achieved before.

The response of the opt/UV continuum to large amplitude X-ray variability can probe the disc structure in AGN. We request a week long AstroSat observation of the NLS1 Ark~564 accreting at near Eddington rate to obtain lightcurves and time-resolved grating spectra with a sampling rate at a fraction of a day. We will measure the wavelength dependent time-lag using the UVIT gratings/filters and the SXT data. We will also study UV continuum spectral variability with grating spectra on short time scales and probe accretion disk heating by X-ray illumination. We will also perform coordinated observations with optical telescopes. The proposed observations will allow us to probe and study the nature of accretion discs in the high accretion rate regime (ie accretion rate close to the Eddington limit), which has not been achieved before.

We propose to use UVIT/ASTROSAT to perform a deep far- and near-ultraviolet survey of one of the fields targeted by the Deep Extragalactic VIsible Legacy Survey (DEVILS). DEVILS is a spectroscopic campaign at the Anglo-Australian Telescope aimed at bridging the near and distant Universe by producing the highest completeness survey of galaxies and groups at intermediate redshifts (0.3

We propose to investigate the ultraviolet imaging of host galaxies in a small sample of radio-selected Narrow line Seyfert 1 galaxies (NLS1s) for a total of 10ks (2x5ks). With UVIT as the primary instrument, our main objective is to understand the nature of connection of host galaxies harboring the NLS1s with their unique radio properties. Along with imaging studies to reveal the host-galaxy morphology, we will also study these targets in the context of their AGN properties. The simultaneous broadband observations in X-rays and the photometric data obtained in ultraviolet will yield measurements of their spectral energy distribution. We will further probe their radio luminosities and corresponding ultraviolet and X-ray luminosities for suspected correlations. The inferred properties and results from this study will be compared with the known observed properties of typical NLS1s. This will further suggest that how these sources connect themselves within the premises of the Unification Scheme.

We propose to investigate the ultraviolet imaging of host galaxies in a small sample of radio-selected Narrow line Seyfert 1 galaxies (NLS1s) for a total of 10ks (2x5ks). With UVIT as the primary instrument, our main objective is to understand the nature of connection of host galaxies harboring the NLS1s with their unique radio properties. Along with imaging studies to reveal the host-galaxy morphology, we will also study these targets in the context of their AGN properties. The simultaneous broadband observations in X-rays and the photometric data obtained in ultraviolet will yield measurements of their spectral energy distribution. We will further probe their radio luminosities and corresponding ultraviolet and X-ray luminosities for suspected correlations. The inferred properties and results from this study will be compared with the known observed properties of typical NLS1s. This will further suggest that how these sources connect themselves within the premises of the Unification Scheme.

We request a 50000 seconds exposure of Centaurus A to study the star formation rate in the southern inner lobe (SIL) and southern middle lobe (SML). Our preliminary analysis found signatures of FUV emission in the SML and candidate star-forming regions using the existing UVIT and GALEX data. A deep observation of the region is required to bring out the faint underlying star-forming structures. As far as we are aware, there are no studies reporting on the UV emission in the SML region. The primary objective of this proposal is to study the UV counterpart of SIL and its extension in the SML. We will derive directly the star formation rate, constrain the AGN activity-driven SFR, and conduct comparative studies using archival data which encompass many wavelengths.

We request a 7-day uninterrupted AstroSat long look on the HBL Mkn 421, to obtain X-ray variability monitoring, and complemented by contemporaneous WEBT (optical/NIR continuum and optical polarization) and FACT (TeV) monitoring. The campaign should occur during 3-15 Jan. 2019, with 26 Mar.-7 Apr. 2019 as a back-up option. Short-term variability properties of Mkn 421 are not thoroughly studied, and our multi-band campaign will allow us to quantify variability fractions, variability amplitudes, and volume filling factors, probe short-term interband correlations, determine the electron energy distribution from synchrotron emission using a forward-fitting technique, and explore the multiplicity of emitting regions contributing to each waveband.

Radio-loud AGN are associated with strongly collimated jets, the origin of which remains unclear. The RL-NLS1s are a special class of RL-AGN characterized by low black hole mass, high accretion rate, and relativistic jet emission. We aim to study the gamma-ray detected RL-NLS1/NLS1-blazar 1H~0323+342. The highly variable emissions from disc/corona component and relativistic jet make the source ideal to investigate the disc-jet connection. We plan coordinated monitoring observations of the source with AstroSat in the X-ray/UV bands, and VLA & GMRT in the radio band. We request for three multi-wavelength observations of 1H~0323+342, separated by 10 days, after 2019 January 22. In each observation, we request a 25~ks exposure with SXT. Using the simultaneous multi-wavelength data of the source, we will (i)derive the broadband SED, and (ii)study the disc-jet coupling by investigating the correlated variability of UV/X-ray properties associated with accretion flow and radio properties related to the jet emission.

We request 192 ks of time to execute AstroSat UVIT observations of six nearby galaxies. These data will reveal the population of newly formed massive stars, which will be analyzed in concert with our ongoing survey of 74 galaxies with ALMA. The ALMA survey maps emission from star-forming molecular gas, and the joint analysis of the UVIT and ALMA data can be used to unravel the underlying physics that drives galaxy-scale star formation with our already-developed theoretical framework. With our first high-resolution survey of star forming gas coming from ALMA, UVIT provides a unique opportunity for progress because of its well matched resolution.

We request 192 ks of time to execute AstroSat UVIT observations of six nearby galaxies. These data will reveal the population of newly formed massive stars, which will be analyzed in concert with our ongoing survey of 74 galaxies with ALMA. The ALMA survey maps emission from star-forming molecular gas, and the joint analysis of the UVIT and ALMA data can be used to unravel the underlying physics that drives galaxy-scale star formation with our already-developed theoretical framework. With our first high-resolution survey of star forming gas coming from ALMA, UVIT provides a unique opportunity for progress because of its well matched resolution.

We request 192 ks of time to execute AstroSat UVIT observations of six nearby galaxies. These data will reveal the population of newly formed massive stars, which will be analyzed in concert with our ongoing survey of 74 galaxies with ALMA. The ALMA survey maps emission from star-forming molecular gas, and the joint analysis of the UVIT and ALMA data can be used to unravel the underlying physics that drives galaxy-scale star formation with our already-developed theoretical framework. With our first high-resolution survey of star forming gas coming from ALMA, UVIT provides a unique opportunity for progress because of its well matched resolution.

We request 192 ks of time to execute AstroSat UVIT observations of six nearby galaxies. These data will reveal the population of newly formed massive stars, which will be analyzed in concert with our ongoing survey of 74 galaxies with ALMA. The ALMA survey maps emission from star-forming molecular gas, and the joint analysis of the UVIT and ALMA data can be used to unravel the underlying physics that drives galaxy-scale star formation with our already-developed theoretical framework. With our first high-resolution survey of star forming gas coming from ALMA, UVIT provides a unique opportunity for progress because of its well matched resolution.

We request 192 ks of time to execute AstroSat UVIT observations of six nearby galaxies. These data will reveal the population of newly formed massive stars, which will be analyzed in concert with our ongoing survey of 74 galaxies with ALMA. The ALMA survey maps emission from star-forming molecular gas, and the joint analysis of the UVIT and ALMA data can be used to unravel the underlying physics that drives galaxy-scale star formation with our already-developed theoretical framework. With our first high-resolution survey of star forming gas coming from ALMA, UVIT provides a unique opportunity for progress because of its well matched resolution.

We request 192 ks of time to execute AstroSat UVIT observations of six nearby galaxies. These data will reveal the population of newly formed massive stars, which will be analyzed in concert with our ongoing survey of 74 galaxies with ALMA. The ALMA survey maps emission from star-forming molecular gas, and the joint analysis of the UVIT and ALMA data can be used to unravel the underlying physics that drives galaxy-scale star formation with our already-developed theoretical framework. With our first high-resolution survey of star forming gas coming from ALMA, UVIT provides a unique opportunity for progress because of its well matched resolution.

Magnetic cataclysmic variables show strong variations in their emitted radiation due to the changes in the flow of accretion matter impacting on the magnetic white dwarfs. The interactions of the ionized accretion matter with the magnetic field and the effective cooling of the hot plasma on the white dwarf surface are the key issues to explain the variability but these are not well understood. Here we propose to study the accretion flow characteristics close to the white dwarf surface for the source V834 Cen. The multi-wavelength observations using ASTROSAT will provide the information about the accretion flow geometry near the surface, the cooling mechanism of the hot accreted material.

Magnetic cataclysmic variables show strong variations in their emitted radiation due to the changes in the flow of accretion matter impacting on the magnetic white dwarfs. The interactions of the ionized accretion matter with the magnetic field and the effective cooling of the hot plasma on the white dwarf surface are the key issues to explain the variability but these are not well understood. Here we propose to study the accretion flow characteristics close to the white dwarf surface for the source V834 Cen. The multi-wavelength observations using ASTROSAT will provide the information about the accretion flow geometry near the surface, the cooling mechanism of the hot accreted material.

Magnetic cataclysmic variables show strong variations in their emitted radiation due to the changes in the flow of accretion matter impacting on the magnetic white dwarfs. The interactions of the ionized accretion matter with the magnetic field and the effective cooling of the hot plasma on the white dwarf surface are the key issues to explain the variability but these are not well understood. Here we propose to study the accretion flow characteristics close to the white dwarf surface for the source V834 Cen. The multi-wavelength observations using ASTROSAT will provide the information about the accretion flow geometry near the surface, the cooling mechanism of the hot accreted material.

Magnetic cataclysmic variables show strong variations in their emitted radiation due to the changes in the flow of accretion matter impacting on the magnetic white dwarfs. The interactions of the ionized accretion matter with the magnetic field and the effective cooling of the hot plasma on the white dwarf surface are the key issues to explain the variability but these are not well understood. Here we propose to study the accretion flow characteristics close to the white dwarf surface for the source V834 Cen. The multi-wavelength observations using ASTROSAT will provide the information about the accretion flow geometry near the surface, the cooling mechanism of the hot accreted material.

Magnetic cataclysmic variables show strong variations in their emitted radiation due to the changes in the flow of accretion matter impacting on the magnetic white dwarfs. The interactions of the ionized accretion matter with the magnetic field and the effective cooling of the hot plasma on the white dwarf surface are the key issues to explain the variability but these are not well understood. Here we propose to study the accretion flow characteristics close to the white dwarf surface for the source V834 Cen. The multi-wavelength observations using ASTROSAT will provide the information about the accretion flow geometry near the surface, the cooling mechanism of the hot accreted material.

The origin and evolution of hydrogen deficient stars is yet a mystery. They are presently thought to be a result of mergers of two white dwarfs. In optical region the extreme helium stars (hot H-deficient stars) show very similar spectral energy distributions as normal (i.e hydrogen rich) O- and B-type stars. Hence, they are not easily distinguishable. This limitation severely restricted the number of stars known as well as searches for them in older stellar aggregates (eg. globular clusters) which are very important consideration for estimating their life times and evolutionary considerations. Atmospheric models of EHes show that even though the optical colours are the same as normal stars the UVIT band colours are clearly different in the temperature range of 8000-30000 K. We propose to calibrate these indices and use them as criteria to discover new EHes and other H-deficient stars in globular clusters including the horizontal branch morphology.

The origin and evolution of hydrogen deficient stars is yet a mystery. They are presently thought to be a result of mergers of two white dwarfs. In optical region the extreme helium stars (hot H-deficient stars) show very similar spectral energy distributions as normal (i.e hydrogen rich) O- and B-type stars. Hence, they are not easily distinguishable. This limitation severely restricted the number of stars known as well as searches for them in older stellar aggregates (eg. globular clusters) which are very important consideration for estimating their life times and evolutionary considerations. Atmospheric models of EHes show that even though the optical colours are the same as normal stars the UVIT band colours are clearly different in the temperature range of 8000-30000 K. We propose to calibrate these indices and use them as criteria to discover new EHes and other H-deficient stars in globular clusters including the horizontal branch morphology.

The origin and evolution of hydrogen deficient stars is yet a mystery. They are presently thought to be a result of mergers of two white dwarfs. In optical region the extreme helium stars (hot H-deficient stars) show very similar spectral energy distributions as normal (i.e hydrogen rich) O- and B-type stars. Hence, they are not easily distinguishable. This limitation severely restricted the number of stars known as well as searches for them in older stellar aggregates (eg. globular clusters) which are very important consideration for estimating their life times and evolutionary considerations. Atmospheric models of EHes show that even though the optical colours are the same as normal stars the UVIT band colours are clearly different in the temperature range of 8000-30000 K. We propose to calibrate these indices and use them as criteria to discover new EHes and other H-deficient stars in globular clusters including the horizontal branch morphology.

The origin and evolution of hydrogen deficient stars is yet a mystery. They are presently thought to be a result of mergers of two white dwarfs. In optical region the extreme helium stars (hot H-deficient stars) show very similar spectral energy distributions as normal (i.e hydrogen rich) O- and B-type stars. Hence, they are not easily distinguishable. This limitation severely restricted the number of stars known as well as searches for them in older stellar aggregates (eg. globular clusters) which are very important consideration for estimating their life times and evolutionary considerations. Atmospheric models of EHes show that even though the optical colours are the same as normal stars the UVIT band colours are clearly different in the temperature range of 8000-30000 K. We propose to calibrate these indices and use them as criteria to discover new EHes and other H-deficient stars in globular clusters including the horizontal branch morphology.

%latex%4U 1608-52 is a neutron star soft X-ray transient having an outburst period of $\sim$ 500 days. Although being one of the fastest spinning neutron stars, it exhibits spectral and temporal properties that are signatures of black holes. Even after extensive studies, its transition of spectral states during outburst decays, occurrence of quasi-periodic oscillations (QPOs) and lags exhibited by QPOs are not clearly understood. Since X-ray instruments on-board {\em AstroSat} can provide simultaneous observations from 0.3 - 80 keV energy range with better spectral and timing resolution, studies on 4U 1608-52 in this broad band during an outburst decay may give us substantial clarity on its spectral states, QPOs and lags. \textbf {Hence, we propose for an anticipated ToO of the source at 5, 10 and 20 days after trigger. We plan to schedule the observation into three 20 ks cycles each using SXT (as primary instrument) and LAXPC}

We ask for ASTROSAT time to observe three flaring red dwarfs: AT Mic, YZ CMi, and EQ Peg; we request 20 ks of observations for each target (60 ks in total). All three stars are known for high activity level, the flares have been detected in different spectral ranges, including X-rays. We expect to detect at least one flare from each star and obtain their X-ray light curves and spectra. We propose to use SXT as the primary instrument and LAXPC and CZTI as secondary instruments. These data will be used to a) estimate the parameters of the thermal and non-thermal electrons in the flares; b) investigate the Neupert effect in the stellar flares and analyze its similarities/differences from the solar case; c) analyze the quasi-periodic oscillations (if detected).

NGC 6814, a Seyfert 1.5 active galaxy, varies strongly on both short (hours) and longer (days/months) time scales. In addition to intrinsic variability, NGC 6814 exhibits rapid absorption variability on scales of fraction of a day. This AGN provides a unique opportunity to probe geometry of the absorber based on X-ray/UV absorption induced variability. Previous X-ray observations with 1 day cadence have found strong correlations and optical/UV reprocessing delay. We request for ~125 ks Astrosat observation with SXT as the primary instrument. This will allow us to probe UV reddening during X-ray eclipses and to measure wavelength dependent UV lags due to X-ray reprocessing. The lags observed for massive AGNs are longer than those predicted by the standard Shakura-Sunyaev disk theory, which should be checked for various masses (here, ~4.7 x less than NGC 5548) and accretion rates. Astrosat will measure the X-ray/UV delay and test the standard disk theory.

We request deep ultra-violet (FUV+NUV) imaging of a sample of eight gas-rich ultra-diffuse galaxies. These systems populate an intriguing threshold region of star formation, below which galaxies show weak/no apparent star formation despite their large reservoirs of neutral gas. Deep, high-resolution UV images are essential to measure the amount of recent star formation and to quantify its spatial distribution. Combined with our extensive multi-wavelength observations, this UV data will help to test the evolutionary pathways between these enigmatic gas-rich UDGs and their recently-identified gas-poor counterparts in clusters.

We request deep ultra-violet (FUV+NUV) imaging of a sample of eight gas-rich ultra-diffuse galaxies. These systems populate an intriguing threshold region of star formation, below which galaxies show weak/no apparent star formation despite their large reservoirs of neutral gas. Deep, high-resolution UV images are essential to measure the amount of recent star formation and to quantify its spatial distribution. Combined with our extensive multi-wavelength observations, this UV data will help to test the evolutionary pathways between these enigmatic gas-rich UDGs and their recently-identified gas-poor counterparts in clusters.

We request deep ultra-violet (FUV+NUV) imaging of a sample of eight gas-rich ultra-diffuse galaxies. These systems populate an intriguing threshold region of star formation, below which galaxies show weak/no apparent star formation despite their large reservoirs of neutral gas. Deep, high-resolution UV images are essential to measure the amount of recent star formation and to quantify its spatial distribution. Combined with our extensive multi-wavelength observations, this UV data will help to test the evolutionary pathways between these enigmatic gas-rich UDGs and their recently-identified gas-poor counterparts in clusters.

We request deep ultra-violet (FUV+NUV) imaging of a sample of eight gas-rich ultra-diffuse galaxies. These systems populate an intriguing threshold region of star formation, below which galaxies show weak/no apparent star formation despite their large reservoirs of neutral gas. Deep, high-resolution UV images are essential to measure the amount of recent star formation and to quantify its spatial distribution. Combined with our extensive multi-wavelength observations, this UV data will help to test the evolutionary pathways between these enigmatic gas-rich UDGs and their recently-identified gas-poor counterparts in clusters.

We propose a long duration observation to continue monitoring of the nearby luminous and highly variable QSO PDS 456 and to use the ASTROSAT instrument complement to unravel the complex behaviour of this and similar objects with a view to elucidating the underlying physical conditions and geometry in the regions responsible for the optical to hard X-ray emission of accreting super-massive black-holes

We propose to carry out a very deep ($\sim 28$~mag) far-ultraviolet imaging survey of the GOODS-South field using UVIT-AstroSat. Such deep FUV observations are necessary to finding low-mass, compact, strongly star-forming galaxies (SFGs) that are potential Lyman continuum (LyC) emitters in the intermediate redshift range. Detection of these LyCs holds the key to our understanding of the level of ionizing radiation in our universe - playing a major role in the cosmological modelling of galaxy formation and evolution. Currently, there has been no direct detection of such sources with redshift $z \sim 1$. With the proposed observation, we will not only be able to place a stringent limit on the LyC detection, we will construct multi-band Spectral energy distribution (SED) (from FUV to FIR) and determine the physical properties such as stellar population, age and metal abundances of these low-mass SFGs. In this proposal we request 44~ksec of UVIT time.

We propose to use UVIT/ASTROSAT to perform a deep far- and near-ultraviolet survey of one of the fields targeted by the Deep Extragalactic VIsible Legacy Survey (DEVILS). DEVILS is a spectroscopic campaign at the Anglo-Australian Telescope aimed at bridging the near and distant Universe by producing the highest completeness survey of galaxies and groups at intermediate redshifts (0.3$&lt;z&lt;$1.0). DEVILS is targeting the same fields that will be observed by the LSST and MeerKAT/LADUMA projects. The primary goal of this proposal is to take advantage of the high resolution of ASTROSAT to determine how the structure of the star-forming disks has changed across environment in the last five billion years. As a by-product, this project will deliver the deepest and highest resolution ultraviolet cataloug of the Chandra Deep Field South region to the community, thus making sure that ASTROSAT will leave a long-lasting legacy to the field of galaxy evolution.

We propose to observe 9 fields in the north-east region of the Small Magellanic Cloud (SMC) known as the Shell within which recent star formation has been detected across multiple wavelengths. The morphology of the Shell, as traced by both main-sequence stars from the near-infrared (IR) to far-ultraviolet, indicates that it is the result of tidal interactions. We plan to combine these UVIT data with optical and near-IR (proprietary) data to study the young stellar population of the Shell and to i) trace the tidal features and their connection to the main body of the SMC, ii) estimate age and spatial distribution of the recently formed stars in the tidal tails and iii) the shape and potential spatial variation of the extinction curve in and around these features.

We propose to observe 9 fields in the north-east region of the Small Magellanic Cloud (SMC) known as the Shell within which recent star formation has been detected across multiple wavelengths. The morphology of the Shell, as traced by both main-sequence stars from the near-infrared (IR) to far-ultraviolet, indicates that it is the result of tidal interactions. We plan to combine these UVIT data with optical and near-IR (proprietary) data to study the young stellar population of the Shell and to i) trace the tidal features and their connection to the main body of the SMC, ii) estimate age and spatial distribution of the recently formed stars in the tidal tails and iii) the shape and potential spatial variation of the extinction curve in and around these features.

We propose to observe 9 fields in the north-east region of the Small Magellanic Cloud (SMC) known as the Shell within which recent star formation has been detected across multiple wavelengths. The morphology of the Shell, as traced by both main-sequence stars from the near-infrared (IR) to far-ultraviolet, indicates that it is the result of tidal interactions. We plan to combine these UVIT data with optical and near-IR (proprietary) data to study the young stellar population of the Shell and to i) trace the tidal features and their connection to the main body of the SMC, ii) estimate age and spatial distribution of the recently formed stars in the tidal tails and iii) the shape and potential spatial variation of the extinction curve in and around these features.

We propose to observe 9 fields in the north-east region of the Small Magellanic Cloud (SMC) known as the Shell within which recent star formation has been detected across multiple wavelengths. The morphology of the Shell, as traced by both main-sequence stars from the near-infrared (IR) to far-ultraviolet, indicates that it is the result of tidal interactions. We plan to combine these UVIT data with optical and near-IR (proprietary) data to study the young stellar population of the Shell and to i) trace the tidal features and their connection to the main body of the SMC, ii) estimate age and spatial distribution of the recently formed stars in the tidal tails and iii) the shape and potential spatial variation of the extinction curve in and around these features.

As part of the series of proposed observations for persistent kHz QPO sources that also exhibit type-1 X- ray bursts, we propose for a total of 80 ks observation for two persistent, bright bursting low mass X-ray binary sources 4U 1735-44 and GX 17+2 (20 ks each), using Astrosat/LAXPC. The main objective of this proposal would be to carry out sensitive and precise measurements of the frequencies and amplitudes of the previously reported pair of kHz QPOs. Since 4U 1735-44 and GX 17+2 are bursting sources, we also aim at detecting bursts and further examine the earlier reports of tentative Burst Oscillations (BO). Such a study will attempt to address one of the long standing uncertainties regarding correlations between the frequency separation of kHz QPOs (f_kHz-QPO-separation), BO frequency (f_BO) and NS spin frequency (f_spin).

As part of the series of proposed observations for persistent kHz QPO sources that also exhibit type-1 X- ray bursts, we propose for a total of 80 ks observation for two persistent, bright bursting low mass X-ray binary sources 4U 1735-44 and GX 17+2 (20 ks each), using Astrosat/LAXPC. The main objective of this proposal would be to carry out sensitive and precise measurements of the frequencies and amplitudes of the previously reported pair of kHz QPOs. Since 4U 1735-44 and GX 17+2 are bursting sources, we also aim at detecting bursts and further examine the earlier reports of tentative Burst Oscillations (BO). Such a study will attempt to address one of the long standing uncertainties regarding correlations between the frequency separation of kHz QPOs (f_kHz-QPO-separation), BO frequency (f_BO) and NS spin frequency (f_spin).

Defying traditional wisdom, several star-forming galaxies have been discovered in galaxy clusters in the last decade. These galaxies are a rare class of transition objects “caught in the act”, and therefore provide essential clues for understanding the evolution of galaxies from being actively star-forming spirals and irregulars in low-density environments, to passively-evolving spheroids in the core of groups and clusters. We propose to image 4 such star-forming galaxies falling into clusters with UVIT. Together with the ancillary optical and infrared data, we will use the AstroSat data to explore the extent of the low surface brightness tidal features and the impact of gas loss on the morphology of the infalling galaxies. We will also study star formation efficiency in these galaxies undergoing tidal stress.

Defying traditional wisdom, several star-forming galaxies have been discovered in galaxy clusters in the last decade. These galaxies are a rare class of transition objects “caught in the act”, and therefore provide essential clues for understanding the evolution of galaxies from being actively star-forming spirals and irregulars in low-density environments, to passively-evolving spheroids in the core of groups and clusters. We propose to image 4 such star-forming galaxies falling into clusters with UVIT. Together with the ancillary optical and infrared data, we will use the AstroSat data to explore the extent of the low surface brightness tidal features and the impact of gas loss on the morphology of the infalling galaxies. We will also study star formation efficiency in these galaxies undergoing tidal stress.

Defying traditional wisdom, several star-forming galaxies have been discovered in galaxy clusters in the last decade. These galaxies are a rare class of transition objects “caught in the act”, and therefore provide essential clues for understanding the evolution of galaxies from being actively star-forming spirals and irregulars in low-density environments, to passively-evolving spheroids in the core of groups and clusters. We propose to image 4 such star-forming galaxies falling into clusters with UVIT. Together with the ancillary optical and infrared data, we will use the AstroSat data to explore the extent of the low surface brightness tidal features and the impact of gas loss on the morphology of the infalling galaxies. We will also study star formation efficiency in these galaxies undergoing tidal stress.

We request a single pointing 40\,ks multi-wavelength observation of the bright High-energy peaked BL Lac Mrk~180 using the SXT, LAXPC and UVIT instruments on-board AstroSat. SXT and LAXPC instruments will provide unprecedented spectral coverage of the synchrotron peak and beyond, which help to constrain the peak securely. Previous observation results of Mrk~180 had shown an evidence of departure of the X-ray spectrum from a power law shape, which is an indication of the spectral curvature. The broadband X-ray coverage of AstroSat can confirm the presence of such curvature. Optical/UV observation with UVIT will give an important piece of information regarding the complex multi-wavelength variability behaviour and origin of the low energy emission. By modelling the broadband SED, which can be obtained from the simultaneous multi-wavelength observation of AstroSat along with {\it Fermi}, we will be able to constrain the physical parameters which provide useful information regarding the underlying physical processes.

M67 cluster is known to have a wide variety of stars which are not supported by the single star evolutionary theory. The most famous among them are the blue straggler stars (BSS), along with the sub-subgiants and yellow stragglers. Mass transfer (MT) in a binary system is the favoured formation mechanism for these stars in open clusters. If these stars indeed are of MT origin, then their expected to have the presence of donor, as an evolved primary star. The detection and identification of evolutionary state of the donor is thus crucial to confirm MT pathway of the formation of these systems. Gosnell et al. (2015) found that about 20% of BSS are formed recently in the old open cluter NGC 188, by detecting hot WD companions using the HST FUV observations. No such detections are there in M67 so far.

The 5000- 8000 yr old Cygnus supernova remnant (SNR), 450 pc away, is optically, UV and x-ray bright, and serves as an excellent laboratory to study the propagation and the interaction of the supernova shock and its ejecta, as the blast wave propagates through the interstellar medium. We request herein Astrosat multiwaveband time to continue our program to map out this SNR in the UV narrow band filters, as well as in soft x-ray (0.3-10 keV) bands. The narrow band UVIT/NUV, and narrow + broad band UVIT/FUV filters trace emission line regions in C IV, He II, and Mg II, our observations will detect and isolate regions of hot (10$^{4-5}$ K) and intermediate (5000- 8000 K) temperatures. Combined with Astrosat/SXT spectra and, archival x-ray and optical data of select fields, this will help determinethe evolving physical conditions as the SN blast wave and ejecta interact with the local ISM.

The 5000- 8000 yr old Cygnus supernova remnant (SNR), 450 pc away, is optically, UV and x-ray bright, and serves as an excellent laboratory to study the propagation and the interaction of the supernova shock and its ejecta, as the blast wave propagates through the interstellar medium. We request herein Astrosat multiwaveband time to continue our program to map out this SNR in the UV narrow band filters, as well as in soft x-ray (0.3-10 keV) bands. The narrow band UVIT/NUV, and narrow + broad band UVIT/FUV filters trace emission line regions in C IV, He II, and Mg II, our observations will detect and isolate regions of hot (10$^{4-5}$ K) and intermediate (5000- 8000 K) temperatures. Combined with Astrosat/SXT spectra and, archival x-ray and optical data of select fields, this will help determinethe evolving physical conditions as the SN blast wave and ejecta interact with the local ISM.

The 5000- 8000 yr old Cygnus supernova remnant (SNR), 450 pc away, is optically, UV and x-ray bright, and serves as an excellent laboratory to study the propagation and the interaction of the supernova shock and its ejecta, as the blast wave propagates through the interstellar medium. We request herein Astrosat multiwaveband time to continue our program to map out this SNR in the UV narrow band filters, as well as in soft x-ray (0.3-10 keV) bands. The narrow band UVIT/NUV, and narrow + broad band UVIT/FUV filters trace emission line regions in C IV, He II, and Mg II, our observations will detect and isolate regions of hot (10$^{4-5}$ K) and intermediate (5000- 8000 K) temperatures. Combined with Astrosat/SXT spectra and, archival x-ray and optical data of select fields, this will help determinethe evolving physical conditions as the SN blast wave and ejecta interact with the local ISM.

The 5000- 8000 yr old Cygnus supernova remnant (SNR), 450 pc away, is optically, UV and x-ray bright, and serves as an excellent laboratory to study the propagation and the interaction of the supernova shock and its ejecta, as the blast wave propagates through the interstellar medium. We request herein Astrosat multiwaveband time to continue our program to map out this SNR in the UV narrow band filters, as well as in soft x-ray (0.3-10 keV) bands. The narrow band UVIT/NUV, and narrow + broad band UVIT/FUV filters trace emission line regions in C IV, He II, and Mg II, our observations will detect and isolate regions of hot (10$^{4-5}$ K) and intermediate (5000- 8000 K) temperatures. Combined with Astrosat/SXT spectra and, archival x-ray and optical data of select fields, this will help determinethe evolving physical conditions as the SN blast wave and ejecta interact with the local ISM.

The 5000- 8000 yr old Cygnus supernova remnant (SNR), 450 pc away, is optically, UV and x-ray bright, and serves as an excellent laboratory to study the propagation and the interaction of the supernova shock and its ejecta, as the blast wave propagates through the interstellar medium. We request herein Astrosat multiwaveband time to continue our program to map out this SNR in the UV narrow band filters, as well as in soft x-ray (0.3-10 keV) bands. The narrow band UVIT/NUV, and narrow + broad band UVIT/FUV filters trace emission line regions in C IV, He II, and Mg II, our observations will detect and isolate regions of hot (10$^{4-5}$ K) and intermediate (5000- 8000 K) temperatures. Combined with Astrosat/SXT spectra and, archival x-ray and optical data of select fields, this will help determinethe evolving physical conditions as the SN blast wave and ejecta interact with the local ISM.

Recent studies have shown that most of the Globular clusters (GCs) have multiple stellar populations. GCs also harbour exotic stars such as blue straggler stars (BSS, products of stellar collision, merger or mass transfer), horizontal branch (HB) and extreme HB stars which are found more in the core of the GCs. The HST treasury is a goldmine for the GC cores (inner 3 arcmin) in the optical and near-UV wavelengths. UVIT has the unique capability to create a complimentary treasury in the Far and near UV passbands, for not only the core, but also the full cluster. We propose to study selected GCs from the HST treasury survey, that have wide field photometry from ground observations. This UVIT+HST+Ground treasury will be a unique data set, covering the entire cluster in the FUV, NUV and optical passbands. We request for 2 FUV and one NUV pass band observations for 8 clusters.

Recent studies have shown that most of the Globular clusters (GCs) have multiple stellar populations. GCs also harbour exotic stars such as blue straggler stars (BSS, products of stellar collision, merger or mass transfer), horizontal branch (HB) and extreme HB stars which are found more in the core of the GCs. The HST treasury is a goldmine for the GC cores (inner 3 arcmin) in the optical and near-UV wavelengths. UVIT has the unique capability to create a complimentary treasury in the Far and near UV passbands, for not only the core, but also the full cluster. We propose to study selected GCs from the HST treasury survey, that have wide field photometry from ground observations. This UVIT+HST+Ground treasury will be a unique data set, covering the entire cluster in the FUV, NUV and optical passbands. We request for 2 FUV and one NUV pass band observations for 8 clusters.

Recent studies have shown that most of the Globular clusters (GCs) have multiple stellar populations. GCs also harbour exotic stars such as blue straggler stars (BSS, products of stellar collision, merger or mass transfer), horizontal branch (HB) and extreme HB stars which are found more in the core of the GCs. The HST treasury is a goldmine for the GC cores (inner 3 arcmin) in the optical and near-UV wavelengths. UVIT has the unique capability to create a complimentary treasury in the Far and near UV passbands, for not only the core, but also the full cluster. We propose to study selected GCs from the HST treasury survey, that have wide field photometry from ground observations. This UVIT+HST+Ground treasury will be a unique data set, covering the entire cluster in the FUV, NUV and optical passbands. We request for 2 FUV and one NUV pass band observations for 8 clusters.

The Cartwheel galaxy is the prototype for the collisional ring galaxies often-used case to illustrate the success of collisional scenario of ring formation. In spite of a wealth of data available for this system, there are still some outstanding issues to be addressed. We propose to obtain high resolution UV images of the Cartwheel, that would enable us to detect, for the first time, UV emission from around 150 star-forming knots that have been detected on the HST and ground-based H alpha images. We expect to detect not only these current star-forming knots but also all knots formed over the past 100 Myr. Specifically, we aim to detect the traces of past star formation in the spokes of the Cartwheel and in the wake of the expanding ring. The UV and optical photometry would allow us to constrain the star formation history in the Cartwheel over the last 100 Myr.

Low-mass galaxies are thought to play a large role in reionizing the Universe at redshifts, z>6. However, due to the lack of high quality UV data on low-mass galaxies, the models used to estimate the escape of radiation are poorly constrained. We propose to use AstroSat-UVIT to greatly improve on the GALEX measured UV spectral slopes for 24 low-mass starforming galaxies at z<0.1 selected from the KISSR survey. AstroSat UVIT filters are uniquely well-suited for these measurements. The proposed observations, combined with already developed theoretical models, will allow us to predict the escape of FUV/ionizing radiation from low-mass galaxies in a more robust way than has been possible to date. These predictions will be key to interpreting studies of the first stars in the early universe that will be performed with the James Webb Space Telescope (JWST).

Low-mass galaxies are thought to play a large role in reionizing the Universe at redshifts, z>6. However, due to the lack of high quality UV data on low-mass galaxies, the models used to estimate the escape of radiation are poorly constrained. We propose to use AstroSat-UVIT to greatly improve on the GALEX measured UV spectral slopes for 24 low-mass starforming galaxies at z<0.1 selected from the KISSR survey. AstroSat UVIT filters are uniquely well-suited for these measurements. The proposed observations, combined with already developed theoretical models, will allow us to predict the escape of FUV/ionizing radiation from low-mass galaxies in a more robust way than has been possible to date. These predictions will be key to interpreting studies of the first stars in the early universe that will be performed with the James Webb Space Telescope (JWST).

Low-mass galaxies are thought to play a large role in reionizing the Universe at redshifts, z>6. However, due to the lack of high quality UV data on low-mass galaxies, the models used to estimate the escape of radiation are poorly constrained. We propose to use AstroSat-UVIT to greatly improve on the GALEX measured UV spectral slopes for 24 low-mass starforming galaxies at z<0.1 selected from the KISSR survey. AstroSat UVIT filters are uniquely well-suited for these measurements. The proposed observations, combined with already developed theoretical models, will allow us to predict the escape of FUV/ionizing radiation from low-mass galaxies in a more robust way than has been possible to date. These predictions will be key to interpreting studies of the first stars in the early universe that will be performed with the James Webb Space Telescope (JWST).

Low-mass galaxies are thought to play a large role in reionizing the Universe at redshifts, z>6. However, due to the lack of high quality UV data on low-mass galaxies, the models used to estimate the escape of radiation are poorly constrained. We propose to use AstroSat-UVIT to greatly improve on the GALEX measured UV spectral slopes for 24 low-mass starforming galaxies at z<0.1 selected from the KISSR survey. AstroSat UVIT filters are uniquely well-suited for these measurements. The proposed observations, combined with already developed theoretical models, will allow us to predict the escape of FUV/ionizing radiation from low-mass galaxies in a more robust way than has been possible to date. These predictions will be key to interpreting studies of the first stars in the early universe that will be performed with the James Webb Space Telescope (JWST).

Low-mass galaxies are thought to play a large role in reionizing the Universe at redshifts, z>6. However, due to the lack of high quality UV data on low-mass galaxies, the models used to estimate the escape of radiation are poorly constrained. We propose to use AstroSat-UVIT to greatly improve on the GALEX measured UV spectral slopes for 24 low-mass starforming galaxies at z<0.1 selected from the KISSR survey. AstroSat UVIT filters are uniquely well-suited for these measurements. The proposed observations, combined with already developed theoretical models, will allow us to predict the escape of FUV/ionizing radiation from low-mass galaxies in a more robust way than has been possible to date. These predictions will be key to interpreting studies of the first stars in the early universe that will be performed with the James Webb Space Telescope (JWST).

Low-mass galaxies are thought to play a large role in reionizing the Universe at redshifts, z>6. However, due to the lack of high quality UV data on low-mass galaxies, the models used to estimate the escape of radiation are poorly constrained. We propose to use AstroSat-UVIT to greatly improve on the GALEX measured UV spectral slopes for 24 low-mass starforming galaxies at z<0.1 selected from the KISSR survey. AstroSat UVIT filters are uniquely well-suited for these measurements. The proposed observations, combined with already developed theoretical models, will allow us to predict the escape of FUV/ionizing radiation from low-mass galaxies in a more robust way than has been possible to date. These predictions will be key to interpreting studies of the first stars in the early universe that will be performed with the James Webb Space Telescope (JWST).

Low-mass galaxies are thought to play a large role in reionizing the Universe at redshifts, z>6. However, due to the lack of high quality UV data on low-mass galaxies, the models used to estimate the escape of radiation are poorly constrained. We propose to use AstroSat-UVIT to greatly improve on the GALEX measured UV spectral slopes for 24 low-mass starforming galaxies at z<0.1 selected from the KISSR survey. AstroSat UVIT filters are uniquely well-suited for these measurements. The proposed observations, combined with already developed theoretical models, will allow us to predict the escape of FUV/ionizing radiation from low-mass galaxies in a more robust way than has been possible to date. These predictions will be key to interpreting studies of the first stars in the early universe that will be performed with the James Webb Space Telescope (JWST).

Low-mass galaxies are thought to play a large role in reionizing the Universe at redshifts, z>6. However, due to the lack of high quality UV data on low-mass galaxies, the models used to estimate the escape of radiation are poorly constrained. We propose to use AstroSat-UVIT to greatly improve on the GALEX measured UV spectral slopes for 24 low-mass starforming galaxies at z<0.1 selected from the KISSR survey. AstroSat UVIT filters are uniquely well-suited for these measurements. The proposed observations, combined with already developed theoretical models, will allow us to predict the escape of FUV/ionizing radiation from low-mass galaxies in a more robust way than has been possible to date. These predictions will be key to interpreting studies of the first stars in the early universe that will be performed with the James Webb Space Telescope (JWST).

Low-mass galaxies are thought to play a large role in reionizing the Universe at redshifts, z>6. However, due to the lack of high quality UV data on low-mass galaxies, the models used to estimate the escape of radiation are poorly constrained. We propose to use AstroSat-UVIT to greatly improve on the GALEX measured UV spectral slopes for 24 low-mass starforming galaxies at z<0.1 selected from the KISSR survey. AstroSat UVIT filters are uniquely well-suited for these measurements. The proposed observations, combined with already developed theoretical models, will allow us to predict the escape of FUV/ionizing radiation from low-mass galaxies in a more robust way than has been possible to date. These predictions will be key to interpreting studies of the first stars in the early universe that will be performed with the James Webb Space Telescope (JWST).

Low-mass galaxies are thought to play a large role in reionizing the Universe at redshifts, z>6. However, due to the lack of high quality UV data on low-mass galaxies, the models used to estimate the escape of radiation are poorly constrained. We propose to use AstroSat-UVIT to greatly improve on the GALEX measured UV spectral slopes for 24 low-mass starforming galaxies at z<0.1 selected from the KISSR survey. AstroSat UVIT filters are uniquely well-suited for these measurements. The proposed observations, combined with already developed theoretical models, will allow us to predict the escape of FUV/ionizing radiation from low-mass galaxies in a more robust way than has been possible to date. These predictions will be key to interpreting studies of the first stars in the early universe that will be performed with the James Webb Space Telescope (JWST).

The UV excess recently observed in 7 Blue Straggler Stars (BSSs) in the open cluster NGC188 (Gosnell2015) has been interpreted as the photometric signature of hot and young white dwarf (WD) companions. Ferraro2006 discovered a sub-sample of BSSs in 47Tucanae showing carbon (C) and oxygen (O) depletion with respect to normal cluster stars which has been considered as the chemical signature of recent MT activity from a companion star, in which case the observed BSSs should be orbited by hot He-WDs. Here we propose UVIT far-UV photometry of 47Tuc to search for the suspected WD companions to BSSs. The appropriate combination of three FUV filters allow the construction of two narrow band-passes well suitable to properly detect the UV emission of the expected WDs which will allow us to unveil the combined (photometric and spectroscopic) signature of the MT formation channel of BSS in GCs.

We request one 40 ksec observation of the Neutron Star LMXB MXB 1730-335 (the ‘Rapid Burster’) during its next outburst. In previous outbursts, the Rapid Burster has displayed complex ‘classes’ of variability previously only seen in the Black Hole LMXBs GRS 1915+105 and IGR J17091-3624. Only 2 classes have been observed in the Rapid Burster, compared to 15 and 9 respectively in GRS 1915+105 and IGR J17091-3624. With LAXPC and SXT we aim to observe and perform phase-resolved spectroscopy of an additional class in the Rapid Burster, and the presence or absence of this class will allow us to quantify the role of the compact object in GRS 1915-like variability. We also expect to observe many (~100) Type I and Type II X-Ray Bursts, allowing us to further burst population studies performed by previous authors. This is an updated resubmit of proposal AO4 207, which was accepted but not triggered.

We propose to map the UV emission around dual nuclei in late-stage galaxy mergers and interacting systems. Our targets have been observed by GALEX but not with the Hubble Space Telescope UVIS camera. The higher spatial resolution of UVIT compared to GALEX will help us resolve the dual cores and study the disk star-formation triggered by the merging process. Our targets are all low redshift, UV bright sources. We have observed a total of 11 merging galaxies with dual nuclei in previous ASTROSAT cycles and the preliminary results have been presented in meetings in India. With the help of the radio and optical follow-up observations, we have confirmed Dual AGN in a few targets. We have found signatures of AGN-feedback induced star-formation in some of the galaxies using the UVIT data. Hence we have selected four more merger remnants to increase the sample for a better statistical sample.

We propose to map the UV emission around dual nuclei in late-stage galaxy mergers and interacting systems. Our targets have been observed by GALEX but not with the Hubble Space Telescope UVIS camera. The higher spatial resolution of UVIT compared to GALEX will help us resolve the dual cores and study the disk star-formation triggered by the merging process. Our targets are all low redshift, UV bright sources. We have observed a total of 11 merging galaxies with dual nuclei in previous ASTROSAT cycles and the preliminary results have been presented in meetings in India. With the help of the radio and optical follow-up observations, we have confirmed Dual AGN in a few targets. We have found signatures of AGN-feedback induced star-formation in some of the galaxies using the UVIT data. Hence we have selected four more merger remnants to increase the sample for a better statistical sample.

We propose to map the UV emission around dual nuclei in late-stage galaxy mergers and interacting systems. Our targets have been observed by GALEX but not with the Hubble Space Telescope UVIS camera. The higher spatial resolution of UVIT compared to GALEX will help us resolve the dual cores and study the disk star-formation triggered by the merging process. Our targets are all low redshift, UV bright sources. We have observed a total of 11 merging galaxies with dual nuclei in previous ASTROSAT cycles and the preliminary results have been presented in meetings in India. With the help of the radio and optical follow-up observations, we have confirmed Dual AGN in a few targets. We have found signatures of AGN-feedback induced star-formation in some of the galaxies using the UVIT data. Hence we have selected four more merger remnants to increase the sample for a better statistical sample.

We propose to map the UV emission around dual nuclei in late-stage galaxy mergers and interacting systems. Our targets have been observed by GALEX but not with the Hubble Space Telescope UVIS camera. The higher spatial resolution of UVIT compared to GALEX will help us resolve the dual cores and study the disk star-formation triggered by the merging process. Our targets are all low redshift, UV bright sources. We have observed a total of 11 merging galaxies with dual nuclei in previous ASTROSAT cycles and the preliminary results have been presented in meetings in India. With the help of the radio and optical follow-up observations, we have confirmed Dual AGN in a few targets. We have found signatures of AGN-feedback induced star-formation in some of the galaxies using the UVIT data. Hence we have selected four more merger remnants to increase the sample for a better statistical sample.

Globular Clusters (GCs) house exotic stellar populations and are the only sites where the products of direct collision of stars (Blue Straggler stars, BSS) are found. GCs also have accreting binaries, WDs and Horizontal branch stars, which are all bright in the UV. In the UV, all these stars stand out from the swamp of the cooler main-sequence stars and red giants. Our study on NGC 1851 (Subramaniam et al. 2017) suggest that the colour-magnitude diagrams using UVIT filters create definite diagnostic regions which can be used to detect and identify these systems. Exploiting the resolution and filter system of the UVIT, we plan to derive the multi-wavelength SEDs and estimate the fundamental properties such as mass, temperature and Luminosity. NGC 5272 (M3) is one such cluster with many UV bright stars located in the cluster.

Elliptical galaxies are further classified into core ellipticals and core-less ellipticals based on their physical properties and evolution mechanisms. Kormendy et.al (2009) suggests core ellipticals are made up of old stars that are enhanced in alpha elements on the other hand core-less ellipticals are made up of young stars with near solar compositions. The UV flux is one of the best tracers of the current star formation in galaxies provided there is only limited dust present in the system. In this study, we request deep UVIT observations at the centres of six nearby elliptical galaxies which consisting of equal number of core and core-less galaxies. Further, the central intensity of galaxies is found to correlate well with the mass of central supermassive blackhole. Hence, we propose to study the central region of these galaxies in UV in an attempt to understand its connection with the evolution of galaxies.

Elliptical galaxies are further classified into core ellipticals and core-less ellipticals based on their physical properties and evolution mechanisms. Kormendy et.al (2009) suggests core ellipticals are made up of old stars that are enhanced in alpha elements on the other hand core-less ellipticals are made up of young stars with near solar compositions. The UV flux is one of the best tracers of the current star formation in galaxies provided there is only limited dust present in the system. In this study, we request deep UVIT observations at the centres of six nearby elliptical galaxies which consisting of equal number of core and core-less galaxies. Further, the central intensity of galaxies is found to correlate well with the mass of central supermassive blackhole. Hence, we propose to study the central region of these galaxies in UV in an attempt to understand its connection with the evolution of galaxies.

We ask for deep UV imaging of the galaxy JW108 and its surrounding galaxy cluster Abell 3376, to make a combined UV and optical IFU study of the advanced stage of galaxy gas stripping. In JW108 ram pressure stripping has removed all the gas from the disk except in the central region and has created a tail of unilateral ionized gas debris where new stars are formed. We will study the star-forming regions in the disk and the tails, in particular the formation and evolution of the stellar clumps outside of the galaxy disk. The UVIT data will allow us to study how the quenching proceeds within the galaxy disk, using the UV flux from recently born stars. Finally, we will obtain a census of galaxies with UV tails within 800kpc from JW108, and a color-map of galaxies to study spatially resolved star-formation.

The aim of this proposal is to investigate in detail the observed UV star counts obtained by UVIT-ASTROSAT vis-a-vis the model simulated catalogues produced by the Besancon model of stellar population synthesis in several Galactic directions, and to explore the potential for studying the structure of our Galaxy from images in multiple NUV and FUV filters of the UVIT. UV star counts will be dominated by main-sequence (MS) stars, hot white dwarfs (WDs) and blue horizontal branch stars (BHBs), and hence will be very useful to separate out different stellar populations since we have several UV colours, which in turn will help us to estimate the structural parameters of the Galaxy with better precision. The population of WDs and BHBs is also integral to the study of stellar evolution and structure of the Milky Way as they belong to different stellar populations of the Galaxy.

The aim of this proposal is to investigate in detail the observed UV star counts obtained by UVIT-ASTROSAT vis-a-vis the model simulated catalogues produced by the Besancon model of stellar population synthesis in several Galactic directions, and to explore the potential for studying the structure of our Galaxy from images in multiple NUV and FUV filters of the UVIT. UV star counts will be dominated by main-sequence (MS) stars, hot white dwarfs (WDs) and blue horizontal branch stars (BHBs), and hence will be very useful to separate out different stellar populations since we have several UV colours, which in turn will help us to estimate the structural parameters of the Galaxy with better precision. The population of WDs and BHBs is also integral to the study of stellar evolution and structure of the Milky Way as they belong to different stellar populations of the Galaxy.

The aim of this proposal is to investigate in detail the observed UV star counts obtained by UVIT-ASTROSAT vis-a-vis the model simulated catalogues produced by the Besancon model of stellar population synthesis in several Galactic directions, and to explore the potential for studying the structure of our Galaxy from images in multiple NUV and FUV filters of the UVIT. UV star counts will be dominated by main-sequence (MS) stars, hot white dwarfs (WDs) and blue horizontal branch stars (BHBs), and hence will be very useful to separate out different stellar populations since we have several UV colours, which in turn will help us to estimate the structural parameters of the Galaxy with better precision. The population of WDs and BHBs is also integral to the study of stellar evolution and structure of the Milky Way as they belong to different stellar populations of the Galaxy.

We propose for a 50 ks observation of a Be/X-ray binary system RX J0440.9+4431 during an outburst to study the peculiar dip structure in the pulse phase. The variation of the spectral parameters across the dip will enable us to learn more about the accretion geometry near the pole of the Neutron star. The study of the pulse profile and the evolution of the spin period can help in constraining the magnetic field and accretion geometry of the source. Detection of the cyclotron line can help in providing additional verification of the measurement of magnetic field. In this study, we plan to understand the structure of the dip using pulse-phase resolved spectroscopy and attempt to detect the cyclotron line in the phase-averaged spectrum.

%\rm{Mrk 382} is a bright narrow-line Seyfert 1 galaxy having a mass $\sim3\times10^{6}M_{\odot}$. It has very high accretion rate and exhibits rapid variability in the optical to X-ray bands. Despite these peculiar properties, the source has never been probed in detail. Using the capabilities of \textit{AstroSat}, we intend to probe the mechanism that drives the observed rapid variability as a test of the standard accretion disk theory of active galactic nuclei (AGNs). This is especially important because recent \textit{Swift} monitorings have shown that while the optical/UV variability of AGNs mostly results from reprocessing of X-rays in the disk, the measured lags are about three times longer than predicted. We will also check for Comptonisation lags where seed UV photons are upscattered into X-rays in the corona. The expected lag time-scales are $\sim10-15\,\mathrm{ks}$. To achieve these goals, we request $20\,\mathrm{ks}$ observing time for \rm{Mrk 382} with UVIT as the primary instrument.%

%latex%Supersoft X-ray sources (SSSs) are highly luminous, low-$kT$ ($\sim$15-80~eV) sources, interpreted as steady thermonuclear burning on the surface of a white dwarf accreting at an extreme rate from its companion. Reprocessing in the surrounding envelope leads to high optical and UV fluxes. Maintaining the high $\dot{M}$ requires either a high-mass donor or extreme irradiation of a low-mass donor to drive a wind, but no direct donor observations have been made yet. In AO-3 and AO-4, we obtained SXT/FUV/NUV data of the known eclipsing SSS CAL87 (LMC, $P_{\rm orb}=10.6{\rm~hr}$) and the new SSS transient ASASSN-16oh (SMC, $P_{\rm orb}>5{\rm~d}$), demonstrating that these instruments are ideal for observing SSS. We propose to obtain similar SXT/FUV/NUV observations of five other Magellanic Cloud SSS, to undertake systematic modelling of the disc, disc-wind and SSS components for the first time. This could provide constraints on SSS evolution, which is essential in their SN~Ia progenitor candidacy.

%latex%Supersoft X-ray sources (SSSs) are highly luminous, low-$kT$ ($\sim$15-80~eV) sources, interpreted as steady thermonuclear burning on the surface of a white dwarf accreting at an extreme rate from its companion. Reprocessing in the surrounding envelope leads to high optical and UV fluxes. Maintaining the high $\dot{M}$ requires either a high-mass donor or extreme irradiation of a low-mass donor to drive a wind, but no direct donor observations have been made yet. In AO-3 and AO-4, we obtained SXT/FUV/NUV data of the known eclipsing SSS CAL87 (LMC, $P_{\rm orb}=10.6{\rm~hr}$) and the new SSS transient ASASSN-16oh (SMC, $P_{\rm orb}>5{\rm~d}$), demonstrating that these instruments are ideal for observing SSS. We propose to obtain similar SXT/FUV/NUV observations of five other Magellanic Cloud SSS, to undertake systematic modelling of the disc, disc-wind and SSS components for the first time. This could provide constraints on SSS evolution, which is essential in their SN~Ia progenitor candidacy.

We propose to use the ASTROSAT/UVIT to perform a deep, near- and far-ultraviolet survey of 6 patches chosen from the Sloan Great Wall (SGW) which is about 150-300 mega parsec wide and covers a redshift range from 0.07 to 0.15. The main goal of the proposal is to investigate the structural properties, temporal evolution and the effect of environment on the spatially resolved star-forming regions in galaxies in the SGW using ASTROSAT/UVIT. High resolution of UVIT will also leverage to perform the UV surface photometry and to investigate the nature and extent of the UV disks in galaxies along SGW. The proposed science goals will also be greatly benefited in synergy with SDSS which share a comparable resolution with UVIT. We request for a total 24 ksec of observational time to fulfil the goals of this proposal.

We propose to study the UV emission from a sample of 10 closely interacting, spiral galaxies that show evidence of star formation in their galaxy disks and tidal tails. These observations can help us understand the role of mergers in the formation of massive galaxies in our Universe. The AGN activity and enhanced star formation also leads to winds that enrich the galaxy environments. We have already done near-infrared (NIR) observations of the sample using the 1m NIR South African Astronomical Observatory and the galaxies have been detected by Galex. We have checked that the sample is safe to be observed by the UVIT and have adequate UV flux. The higher sensitivity and spatial resolution of UVIT compared to GALEX will help us image the UV emission from the tidal arms/bridges, detect tidal dwarf galaxies (TDGs), isolate massive star forming regions and separate the AGN UV emission from the disk.

We propose to study the UV emission from a sample of 10 closely interacting, spiral galaxies that show evidence of star formation in their galaxy disks and tidal tails. These observations can help us understand the role of mergers in the formation of massive galaxies in our Universe. The AGN activity and enhanced star formation also leads to winds that enrich the galaxy environments. We have already done near-infrared (NIR) observations of the sample using the 1m NIR South African Astronomical Observatory and the galaxies have been detected by Galex. We have checked that the sample is safe to be observed by the UVIT and have adequate UV flux. The higher sensitivity and spatial resolution of UVIT compared to GALEX will help us image the UV emission from the tidal arms/bridges, detect tidal dwarf galaxies (TDGs), isolate massive star forming regions and separate the AGN UV emission from the disk.

We propose to study the UV emission from a sample of 10 closely interacting, spiral galaxies that show evidence of star formation in their galaxy disks and tidal tails. These observations can help us understand the role of mergers in the formation of massive galaxies in our Universe. The AGN activity and enhanced star formation also leads to winds that enrich the galaxy environments. We have already done near-infrared (NIR) observations of the sample using the 1m NIR South African Astronomical Observatory and the galaxies have been detected by Galex. We have checked that the sample is safe to be observed by the UVIT and have adequate UV flux. The higher sensitivity and spatial resolution of UVIT compared to GALEX will help us image the UV emission from the tidal arms/bridges, detect tidal dwarf galaxies (TDGs), isolate massive star forming regions and separate the AGN UV emission from the disk.

We propose to study the UV emission from a sample of 10 closely interacting, spiral galaxies that show evidence of star formation in their galaxy disks and tidal tails. These observations can help us understand the role of mergers in the formation of massive galaxies in our Universe. The AGN activity and enhanced star formation also leads to winds that enrich the galaxy environments. We have already done near-infrared (NIR) observations of the sample using the 1m NIR South African Astronomical Observatory and the galaxies have been detected by Galex. We have checked that the sample is safe to be observed by the UVIT and have adequate UV flux. The higher sensitivity and spatial resolution of UVIT compared to GALEX will help us image the UV emission from the tidal arms/bridges, detect tidal dwarf galaxies (TDGs), isolate massive star forming regions and separate the AGN UV emission from the disk.

We propose to study the UV emission from a sample of 10 closely interacting, spiral galaxies that show evidence of star formation in their galaxy disks and tidal tails. These observations can help us understand the role of mergers in the formation of massive galaxies in our Universe. The AGN activity and enhanced star formation also leads to winds that enrich the galaxy environments. We have already done near-infrared (NIR) observations of the sample using the 1m NIR South African Astronomical Observatory and the galaxies have been detected by Galex. We have checked that the sample is safe to be observed by the UVIT and have adequate UV flux. The higher sensitivity and spatial resolution of UVIT compared to GALEX will help us image the UV emission from the tidal arms/bridges, detect tidal dwarf galaxies (TDGs), isolate massive star forming regions and separate the AGN UV emission from the disk.

We propose to study the UV emission from a sample of 10 closely interacting, spiral galaxies that show evidence of star formation in their galaxy disks and tidal tails. These observations can help us understand the role of mergers in the formation of massive galaxies in our Universe. The AGN activity and enhanced star formation also leads to winds that enrich the galaxy environments. We have already done near-infrared (NIR) observations of the sample using the 1m NIR South African Astronomical Observatory and the galaxies have been detected by Galex. We have checked that the sample is safe to be observed by the UVIT and have adequate UV flux. The higher sensitivity and spatial resolution of UVIT compared to GALEX will help us image the UV emission from the tidal arms/bridges, detect tidal dwarf galaxies (TDGs), isolate massive star forming regions and separate the AGN UV emission from the disk.

We propose to study the UV emission from a sample of 10 closely interacting, spiral galaxies that show evidence of star formation in their galaxy disks and tidal tails. These observations can help us understand the role of mergers in the formation of massive galaxies in our Universe. The AGN activity and enhanced star formation also leads to winds that enrich the galaxy environments. We have already done near-infrared (NIR) observations of the sample using the 1m NIR South African Astronomical Observatory and the galaxies have been detected by Galex. We have checked that the sample is safe to be observed by the UVIT and have adequate UV flux. The higher sensitivity and spatial resolution of UVIT compared to GALEX will help us image the UV emission from the tidal arms/bridges, detect tidal dwarf galaxies (TDGs), isolate massive star forming regions and separate the AGN UV emission from the disk.

We propose to study the UV emission from a sample of 10 closely interacting, spiral galaxies that show evidence of star formation in their galaxy disks and tidal tails. These observations can help us understand the role of mergers in the formation of massive galaxies in our Universe. The AGN activity and enhanced star formation also leads to winds that enrich the galaxy environments. We have already done near-infrared (NIR) observations of the sample using the 1m NIR South African Astronomical Observatory and the galaxies have been detected by Galex. We have checked that the sample is safe to be observed by the UVIT and have adequate UV flux. The higher sensitivity and spatial resolution of UVIT compared to GALEX will help us image the UV emission from the tidal arms/bridges, detect tidal dwarf galaxies (TDGs), isolate massive star forming regions and separate the AGN UV emission from the disk.

We propose to study the UV emission from a sample of 10 closely interacting, spiral galaxies that show evidence of star formation in their galaxy disks and tidal tails. These observations can help us understand the role of mergers in the formation of massive galaxies in our Universe. The AGN activity and enhanced star formation also leads to winds that enrich the galaxy environments. We have already done near-infrared (NIR) observations of the sample using the 1m NIR South African Astronomical Observatory and the galaxies have been detected by Galex. We have checked that the sample is safe to be observed by the UVIT and have adequate UV flux. The higher sensitivity and spatial resolution of UVIT compared to GALEX will help us image the UV emission from the tidal arms/bridges, detect tidal dwarf galaxies (TDGs), isolate massive star forming regions and separate the AGN UV emission from the disk.

We propose to study the UV emission from a sample of 10 closely interacting, spiral galaxies that show evidence of star formation in their galaxy disks and tidal tails. These observations can help us understand the role of mergers in the formation of massive galaxies in our Universe. The AGN activity and enhanced star formation also leads to winds that enrich the galaxy environments. We have already done near-infrared (NIR) observations of the sample using the 1m NIR South African Astronomical Observatory and the galaxies have been detected by Galex. We have checked that the sample is safe to be observed by the UVIT and have adequate UV flux. The higher sensitivity and spatial resolution of UVIT compared to GALEX will help us image the UV emission from the tidal arms/bridges, detect tidal dwarf galaxies (TDGs), isolate massive star forming regions and separate the AGN UV emission from the disk.

The discovery of a novel FUV lobes and jets around NGC 6302 by UVIT opened a new window into the study of planetary nebulae. We would like to further this study to more young planetary nebulae.

The discovery of a novel FUV lobes and jets around NGC 6302 by UVIT opened a new window into the study of planetary nebulae. We would like to further this study to more young planetary nebulae.

The discovery of a novel FUV lobes and jets around NGC 6302 by UVIT opened a new window into the study of planetary nebulae. We would like to further this study to more young planetary nebulae.

The discovery of a novel FUV lobes and jets around NGC 6302 by UVIT opened a new window into the study of planetary nebulae. We would like to further this study to more young planetary nebulae.

We propose to study the UV emission from a sample of 8 interacting galaxies from the ARP catalog that have bright, star forming disks, extended tidal tails or bridges and are at different stages of merging. The tidal structures are bright at UV wavelengths and some have clumps associated with tidal dwarf galaxies. Most of them also have one or more bright active galactic nuclei (AGN). The galaxies are nearby and have sizes of several arcminutes. The high sensitivity and spatial resolution of UVIT will enable us to isolate massive star forming regions in the disks, tails, bridges and separate the AGN from the disk UV emission. We will compare the star formation rates, colors and metallicities over different parts of the galaxies and model the ages of the star forming regions. We will also study how the nuclear activity and star formation enrich the environment around the galaxies.

We propose to study the UV emission from a sample of 8 interacting galaxies from the ARP catalog that have bright, star forming disks, extended tidal tails or bridges and are at different stages of merging. The tidal structures are bright at UV wavelengths and some have clumps associated with tidal dwarf galaxies. Most of them also have one or more bright active galactic nuclei (AGN). The galaxies are nearby and have sizes of several arcminutes. The high sensitivity and spatial resolution of UVIT will enable us to isolate massive star forming regions in the disks, tails, bridges and separate the AGN from the disk UV emission. We will compare the star formation rates, colors and metallicities over different parts of the galaxies and model the ages of the star forming regions. We will also study how the nuclear activity and star formation enrich the environment around the galaxies.

We propose to study the UV emission from a sample of 8 interacting galaxies from the ARP catalog that have bright, star forming disks, extended tidal tails or bridges and are at different stages of merging. The tidal structures are bright at UV wavelengths and some have clumps associated with tidal dwarf galaxies. Most of them also have one or more bright active galactic nuclei (AGN). The galaxies are nearby and have sizes of several arcminutes. The high sensitivity and spatial resolution of UVIT will enable us to isolate massive star forming regions in the disks, tails, bridges and separate the AGN from the disk UV emission. We will compare the star formation rates, colors and metallicities over different parts of the galaxies and model the ages of the star forming regions. We will also study how the nuclear activity and star formation enrich the environment around the galaxies.

We propose to study the UV emission from a sample of 8 interacting galaxies from the ARP catalog that have bright, star forming disks, extended tidal tails or bridges and are at different stages of merging. The tidal structures are bright at UV wavelengths and some have clumps associated with tidal dwarf galaxies. Most of them also have one or more bright active galactic nuclei (AGN). The galaxies are nearby and have sizes of several arcminutes. The high sensitivity and spatial resolution of UVIT will enable us to isolate massive star forming regions in the disks, tails, bridges and separate the AGN from the disk UV emission. We will compare the star formation rates, colors and metallicities over different parts of the galaxies and model the ages of the star forming regions. We will also study how the nuclear activity and star formation enrich the environment around the galaxies.

We propose to study the UV emission from a sample of 8 interacting galaxies from the ARP catalog that have bright, star forming disks, extended tidal tails or bridges and are at different stages of merging. The tidal structures are bright at UV wavelengths and some have clumps associated with tidal dwarf galaxies. Most of them also have one or more bright active galactic nuclei (AGN). The galaxies are nearby and have sizes of several arcminutes. The high sensitivity and spatial resolution of UVIT will enable us to isolate massive star forming regions in the disks, tails, bridges and separate the AGN from the disk UV emission. We will compare the star formation rates, colors and metallicities over different parts of the galaxies and model the ages of the star forming regions. We will also study how the nuclear activity and star formation enrich the environment around the galaxies.

We propose to study the UV emission from a sample of 8 interacting galaxies from the ARP catalog that have bright, star forming disks, extended tidal tails or bridges and are at different stages of merging. The tidal structures are bright at UV wavelengths and some have clumps associated with tidal dwarf galaxies. Most of them also have one or more bright active galactic nuclei (AGN). The galaxies are nearby and have sizes of several arcminutes. The high sensitivity and spatial resolution of UVIT will enable us to isolate massive star forming regions in the disks, tails, bridges and separate the AGN from the disk UV emission. We will compare the star formation rates, colors and metallicities over different parts of the galaxies and model the ages of the star forming regions. We will also study how the nuclear activity and star formation enrich the environment around the galaxies.

We propose to study the UV emission from a sample of 8 interacting galaxies from the ARP catalog that have bright, star forming disks, extended tidal tails or bridges and are at different stages of merging. The tidal structures are bright at UV wavelengths and some have clumps associated with tidal dwarf galaxies. Most of them also have one or more bright active galactic nuclei (AGN). The galaxies are nearby and have sizes of several arcminutes. The high sensitivity and spatial resolution of UVIT will enable us to isolate massive star forming regions in the disks, tails, bridges and separate the AGN from the disk UV emission. We will compare the star formation rates, colors and metallicities over different parts of the galaxies and model the ages of the star forming regions. We will also study how the nuclear activity and star formation enrich the environment around the galaxies.

We propose to study the UV emission from a sample of 8 interacting galaxies from the ARP catalog that have bright, star forming disks, extended tidal tails or bridges and are at different stages of merging. The tidal structures are bright at UV wavelengths and some have clumps associated with tidal dwarf galaxies. Most of them also have one or more bright active galactic nuclei (AGN). The galaxies are nearby and have sizes of several arcminutes. The high sensitivity and spatial resolution of UVIT will enable us to isolate massive star forming regions in the disks, tails, bridges and separate the AGN from the disk UV emission. We will compare the star formation rates, colors and metallicities over different parts of the galaxies and model the ages of the star forming regions. We will also study how the nuclear activity and star formation enrich the environment around the galaxies.

We request a total of 90 ksec effective exposure on the blazar Mrk 501 distributed over three pointings of 30 ksec each, with SXT as primary instrument. Our goal is to study in detail the spectral behaviour of Mrk 501 in hard X-rays and TeV gamma rays, combining observations of ASTROSAT and the TeV-instrument FACT. Given the low state of the source for more than three years in both energy bands, we expect to study the low state with unprecedented precision. As the source is generally variable, splitting up the observation provides the possibility to measure and compare different flux states. A comparison with historical high-state data is planned as well. Including optical and GeV data, broad-band spectral energy distributions will be compiled and modeled. This will allow for conclusions on the still highly debated emission mechanism and a comparison of the dominant processes for low and high state.

Galaxies with tentacles of material that appear to be stripped, having a morphology suggestive of ram pressure stripping and found mostly in galaxy clusters are known as Jellyfish galaxies. The optical and H$\alpha$ imaging of these galaxies reveal tidal debris with tails of ionised gas up to 150 Kpc long where new stars are born in knots and end up contributing to the intracluster light. The ongoing star formation in Jellyfish galaxies can be better understand in UV and making use of the spatial resolution of UVIT we plan to study the spatial variation of star formation in these systems. We propose to observe two galaxy clusters at redshift ~ 0.05 with jellfyish galaxies for which we have VLT MUSE Halpha and VLA HI observations. This study will shed more light in to the triggered star formation and galaxy evolution in dense environments.

Galaxies with tentacles of material that appear to be stripped, having a morphology suggestive of ram pressure stripping and found mostly in galaxy clusters are known as Jellyfish galaxies. The optical and H$\alpha$ imaging of these galaxies reveal tidal debris with tails of ionised gas up to 150 Kpc long where new stars are born in knots and end up contributing to the intracluster light. The ongoing star formation in Jellyfish galaxies can be better understand in UV and making use of the spatial resolution of UVIT we plan to study the spatial variation of star formation in these systems. We propose to observe two galaxy clusters at redshift ~ 0.05 with jellfyish galaxies for which we have VLT MUSE Halpha and VLA HI observations. This study will shed more light in to the triggered star formation and galaxy evolution in dense environments.

To better configure the evolutionary history of early-type galaxies(ETGs), we take the GC system as the powerful tool and take same age and metallicity for them. Over the last ten years, our outlook of similar age and metallicity for GC system got modified to a range of ages varying from young ($\sim$ 2 Gyr) to old ($\sim$ 13 Gyr). Studies confirmed the presence of multiple main sequence tracks (multiple stellar populations-MPs) in Galactic GCs, which expanded to extragalactic systems such as M31 and NGC 5128. Compared to age estimations from spectroscopic indices, UV-optical colours provide robust age estimations for MPs in GCs (Bianchi et al. 2007). Using the best possible high-resolution instrument, UVIT onboard ASTROSAT, we propose to study the ETGs in Leo II group. With the aid of UV data in addition to optical, we plan to confirm the presence of MPs in Leo II and precise age estimation.

We propose multi-band UVIT imaging of the next three fields in our survey of the Coma cluster, the archetypal massive galaxy cluster in the nearby universe. Although a wealth of UV, optical and IR imaging, as well as optical spectroscopy, exists for the high- and intermediate-mass galaxies in this dense environment, the origin of their NUV emission remains uncertain (i.e., FUV-upturn leakage vs. residual star formation). Our proposed Astrosat A05 observations, which require 43,995 sec (12.2 hrs) of open shutter time, will significantly improve upon the existing constraints, from GALEX, on the UV emission in these galaxies by sampling the UV SEDs in four distinct wavelength regions — FUV-BaF2 (0.135-0.18µm), NUV-Silica (0.2-0.3µm), NUVB13 (0.23-0.26µm) and NUVB4 (0.25-0.28µm) — and by providing a three-fold improvement in the spatial resolution of the UV emission within individual galaxies.

We propose multi-band UVIT imaging of the next three fields in our survey of the Coma cluster, the archetypal massive galaxy cluster in the nearby universe. Although a wealth of UV, optical and IR imaging, as well as optical spectroscopy, exists for the high- and intermediate-mass galaxies in this dense environment, the origin of their NUV emission remains uncertain (i.e., FUV-upturn leakage vs. residual star formation). Our proposed Astrosat A05 observations, which require 43,995 sec (12.2 hrs) of open shutter time, will significantly improve upon the existing constraints, from GALEX, on the UV emission in these galaxies by sampling the UV SEDs in four distinct wavelength regions — FUV-BaF2 (0.135-0.18µm), NUV-Silica (0.2-0.3µm), NUVB13 (0.23-0.26µm) and NUVB4 (0.25-0.28µm) — and by providing a three-fold improvement in the spatial resolution of the UV emission within individual galaxies.

We propose multi-band UVIT imaging of the next three fields in our survey of the Coma cluster, the archetypal massive galaxy cluster in the nearby universe. Although a wealth of UV, optical and IR imaging, as well as optical spectroscopy, exists for the high- and intermediate-mass galaxies in this dense environment, the origin of their NUV emission remains uncertain (i.e., FUV-upturn leakage vs. residual star formation). Our proposed Astrosat A05 observations, which require 43,995 sec (12.2 hrs) of open shutter time, will significantly improve upon the existing constraints, from GALEX, on the UV emission in these galaxies by sampling the UV SEDs in four distinct wavelength regions — FUV-BaF2 (0.135-0.18µm), NUV-Silica (0.2-0.3µm), NUVB13 (0.23-0.26µm) and NUVB4 (0.25-0.28µm) — and by providing a three-fold improvement in the spatial resolution of the UV emission within individual galaxies.

We propose multiwavelength observations of ASTROSAT for BL Lac object, PKS 2155-304 (z=0.1160). We request 45 ks observation time in total for 3 pointings for 15 ks each, at epochs separated by 15 and 30 days after the first observation. The synchrotron emission of this source shows a mild curvature in UV/X-ray energy band which deviates from a simple power-law model. To investigate the origin of the spectral curvature and the synchrotron spectral behaviour, we developed a model where the escape probability of the electron from an acceleration region is assumed to be energy dependent. The resultant synchrotron spectrum can be successfully fitted with this semi-analytical model. The combined UV and SXT observations are significant to resolve the synchrotron peak of the source. The simultaneous broadband ASTROSAT observations will be very crucial to perform the detailed study of our model, which provides better insight into the physics of blazar jets.

This project will characterize with unprecedented accuracy the young stellar clusters in a sample of four nearby star-forming galaxies, NGC3344 and NGC4214, by combining two highly complementary tools: ultraviolet imagery of the underlying ionizing stellar populations using UVIT (this proposal) with imaging spectroscopy in the visible of the ionized gas using SITELLE. A set of UVIT filters is selected (FUV-F2, FUV-F5, NUV-F2, NUV-F3, NUV-F5, and VIS1) to cover sensitive regions over the spectral energy distribution of young stellar clusters. While SITELLE provides, with a spatial resolution similar to UVIT, a measurement of the gas emission lines, stellar cluster parameters revealed by UVIT will become inputs for a photoionization code used to gather the gas properties. The combined information from the ionized gas and stellar populations will allow us to study the impact of star formation and different mixing mechanisms on the evolution of galaxies.

This project will characterize with unprecedented accuracy the young stellar clusters in a sample of four nearby star-forming galaxies, NGC3344 and NGC4214, by combining two highly complementary tools: ultraviolet imagery of the underlying ionizing stellar populations using UVIT (this proposal) with imaging spectroscopy in the visible of the ionized gas using SITELLE. A set of UVIT filters is selected (FUV-F2, FUV-F5, NUV-F2, NUV-F3, NUV-F5, and VIS1) to cover sensitive regions over the spectral energy distribution of young stellar clusters. While SITELLE provides, with a spatial resolution similar to UVIT, a measurement of the gas emission lines, stellar cluster parameters revealed by UVIT will become inputs for a photoionization code used to gather the gas properties. The combined information from the ionized gas and stellar populations will allow us to study the impact of star formation and different mixing mechanisms on the evolution of galaxies.

Black hole X-ray binaries (BHXBs) cycle through different accretion states rapidly, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous multi-wavelength observations are the optimal tool that exposes this view. However, these campaigns (connecting the evolving accretion inflow and jet outflow) have been achieved rarely. We request triggered 864ks observations by ASTROSAT of a BHXB as it transitions from the hard to the soft state, when the accretion disk and relativistic jets change significantly. We have submitted three proposals (A05_130/A05_129/A05_126), but ask to observe only one BHXB (out of 15 listed targets); we ask that these proposals are treated together, distributing the proposal as 624/192/48ks against Indian/International/Canadian stare-time. Our group is well suited to attain the simultaneous multiwavelength observations that will maximize the scientific legacy of these observations; we will also make ASTROSAT data immediately public and have open procedures for joining our team.

Black hole X-ray binaries (BHXBs) cycle through different accretion states rapidly, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous multi-wavelength observations are the optimal tool that exposes this view. However, these campaigns (connecting the evolving accretion inflow and jet outflow) have been achieved rarely. We request triggered 864ks observations by ASTROSAT of a BHXB as it transitions from the hard to the soft state, when the accretion disk and relativistic jets change significantly. We have submitted three proposals (A05_130/A05_129/A05_126), but ask to observe only one BHXB (out of 15 listed targets); we ask that these proposals are treated together, distributing the proposal as 624/192/48ks against Indian/International/Canadian stare-time. Our group is well suited to attain the simultaneous multiwavelength observations that will maximize the scientific legacy of these observations; we will also make ASTROSAT data immediately public and have open procedures for joining our team.

Black hole X-ray binaries (BHXBs) cycle through different accretion states rapidly, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous multi-wavelength observations are the optimal tool that exposes this view. However, these campaigns (connecting the evolving accretion inflow and jet outflow) have been achieved rarely. We request triggered 864ks observations by ASTROSAT of a BHXB as it transitions from the hard to the soft state, when the accretion disk and relativistic jets change significantly. We have submitted three proposals (A05_130/A05_129/A05_126), but ask to observe only one BHXB (out of 15 listed targets); we ask that these proposals are treated together, distributing the proposal as 624/192/48ks against Indian/International/Canadian stare-time. Our group is well suited to attain the simultaneous multiwavelength observations that will maximize the scientific legacy of these observations; we will also make ASTROSAT data immediately public and have open procedures for joining our team.

Black hole X-ray binaries (BHXBs) cycle through different accretion states rapidly, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous multi-wavelength observations are the optimal tool that exposes this view. However, these campaigns (connecting the evolving accretion inflow and jet outflow) have been achieved rarely. We request triggered 864ks observations by ASTROSAT of a BHXB as it transitions from the hard to the soft state, when the accretion disk and relativistic jets change significantly. We have submitted three proposals (A05_130/A05_129/A05_126), but ask to observe only one BHXB (out of 15 listed targets); we ask that these proposals are treated together, distributing the proposal as 624/192/48ks against Indian/International/Canadian stare-time. Our group is well suited to attain the simultaneous multiwavelength observations that will maximize the scientific legacy of these observations; we will also make ASTROSAT data immediately public and have open procedures for joining our team.

Black hole X-ray binaries (BHXBs) cycle through different accretion states rapidly, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous multi-wavelength observations are the optimal tool that exposes this view. However, these campaigns (connecting the evolving accretion inflow and jet outflow) have been achieved rarely. We request triggered 864ks observations by ASTROSAT of a BHXB as it transitions from the hard to the soft state, when the accretion disk and relativistic jets change significantly. We have submitted three proposals (A05_130/A05_129/A05_126), but ask to observe only one BHXB (out of 15 listed targets); we ask that these proposals are treated together, distributing the proposal as 624/192/48ks against Indian/International/Canadian stare-time. Our group is well suited to attain the simultaneous multiwavelength observations that will maximize the scientific legacy of these observations; we will also make ASTROSAT data immediately public and have open procedures for joining our team.

Globular clusters are known to host many X-ray sources, several of which have been identified as low-mass X-ray binaries (LMXBs) in quiescence. With a yet unknown recurrence time, some of these LMXBs have been seen in outburst. Here we request a 40 ksec AstroSat observation to follow-up and constrain the spectral characteristics of a transient outburst detected from the globular cluster NGC 6440 by any of the current All Sky Monitors. This observation aims particularly at identifying a new transient (neutron star or black hole), searching for coherent pulsations, constraining the broadband spectra, timing features. These observations will be complemented with multi-wavelength campaigns and will help identify the nature of the transient.

Black hole X-ray binaries (BHXBs) cycle through different accretion states rapidly, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous multi-wavelength observations are the optimal tool that exposes this view. However, these campaigns (connecting the evolving accretion inflow and jet outflow) have been achieved rarely. We request triggered 864ks observations by AstroSat of a BHXB as it transitions from the hard to the soft state, when the accretion disk and relativistic jets change significantly. We have submitted three proposals (A05_130/A05_129/A05_126), but ask to observe only one BHXB (out of 15 listed targets); we ask that these proposals are treated together, distributing the proposal as 624/192/48ks against Indian/International/Canadian stare-time allocations. Our group is well suited to attain the simultaneous multiwavelength observations that will maximize the scientific legacy of these observations; we will also make AstroSat data immediately public and have open procedures for joining our team.

Black hole X-ray binaries (BHXBs) cycle through different accretion states rapidly, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous multi-wavelength observations are the optimal tool that exposes this view. However, these campaigns (connecting the evolving accretion inflow and jet outflow) have been achieved rarely. We request triggered 864ks observations by AstroSat of a BHXB as it transitions from the hard to the soft state, when the accretion disk and relativistic jets change significantly. We have submitted three proposals (A05_130/A05_129/A05_126), but ask to observe only one BHXB (out of 15 listed targets); we ask that these proposals are treated together, distributing the proposal as 624/192/48ks against Indian/International/Canadian stare-time allocations. Our group is well suited to attain the simultaneous multiwavelength observations that will maximize the scientific legacy of these observations; we will also make AstroSat data immediately public and have open procedures for joining our team.

Black hole X-ray binaries (BHXBs) cycle through different accretion states rapidly, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous multi-wavelength observations are the optimal tool that exposes this view. However, these campaigns (connecting the evolving accretion inflow and jet outflow) have been achieved rarely. We request triggered 864ks observations by AstroSat of a BHXB as it transitions from the hard to the soft state, when the accretion disk and relativistic jets change significantly. We have submitted three proposals (A05_130/A05_129/A05_126), but ask to observe only one BHXB (out of 15 listed targets); we ask that these proposals are treated together, distributing the proposal as 624/192/48ks against Indian/International/Canadian stare-time allocations. Our group is well suited to attain the simultaneous multiwavelength observations that will maximize the scientific legacy of these observations; we will also make AstroSat data immediately public and have open procedures for joining our team.

Black hole X-ray binaries (BHXBs) cycle through different accretion states rapidly, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous multi-wavelength observations are the optimal tool that exposes this view. However, these campaigns (connecting the evolving accretion inflow and jet outflow) have been achieved rarely. We request triggered 864ks observations by AstroSat of a BHXB as it transitions from the hard to the soft state, when the accretion disk and relativistic jets change significantly. We have submitted three proposals (A05_130/A05_129/A05_126), but ask to observe only one BHXB (out of 15 listed targets); we ask that these proposals are treated together, distributing the proposal as 624/192/48ks against Indian/International/Canadian stare-time allocations. Our group is well suited to attain the simultaneous multiwavelength observations that will maximize the scientific legacy of these observations; we will also make AstroSat data immediately public and have open procedures for joining our team.

Black hole X-ray binaries (BHXBs) cycle through different accretion states rapidly, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous multi-wavelength observations are the optimal tool that exposes this view. However, these campaigns (connecting the evolving accretion inflow and jet outflow) have been achieved rarely. We request triggered 864ks observations by AstroSat of a BHXB as it transitions from the hard to the soft state, when the accretion disk and relativistic jets change significantly. We have submitted three proposals (A05_130/A05_129/A05_126), but ask to observe only one BHXB (out of 15 listed targets); we ask that these proposals are treated together, distributing the proposal as 624/192/48ks against Indian/International/Canadian stare-time allocations. Our group is well suited to attain the simultaneous multiwavelength observations that will maximize the scientific legacy of these observations; we will also make AstroSat data immediately public and have open procedures for joining our team.

Black hole X-ray binaries (BHXBs) cycle through different accretion states rapidly, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous multi-wavelength observations are the optimal tool that exposes this view. However, these campaigns (connecting the evolving accretion inflow and jet outflow) have been achieved rarely. We request triggered 864ks observations by AstroSat of a BHXB as it transitions from the hard to the soft state, when the accretion disk and relativistic jets change significantly. We have submitted three proposals (A05_130/A05_129/A05_126), but ask to observe only one BHXB (out of 15 listed targets); we ask that these proposals are treated together, distributing the proposal as 624/192/48ks against Indian/International/Canadian stare-time allocations. Our group is well suited to attain the simultaneous multiwavelength observations that will maximize the scientific legacy of these observations; we will also make AstroSat data immediately public and have open procedures for joining our team.

Black hole X-ray binaries (BHXBs) cycle through different accretion states rapidly, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous multi-wavelength observations are the optimal tool that exposes this view. However, these campaigns (connecting the evolving accretion inflow and jet outflow) have been achieved rarely. We request triggered 864ks observations by AstroSat of a BHXB as it transitions from the hard to the soft state, when the accretion disk and relativistic jets change significantly. We have submitted three proposals (A05_130/A05_129/A05_126), but ask to observe only one BHXB (out of 15 listed targets); we ask that these proposals are treated together, distributing the proposal as 624/192/48ks against Indian/International/Canadian stare-time allocations. Our group is well suited to attain the simultaneous multiwavelength observations that will maximize the scientific legacy of these observations; we will also make AstroSat data immediately public and have open procedures for joining our team.

Black hole X-ray binaries (BHXBs) cycle through different accretion states rapidly, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous multi-wavelength observations are the optimal tool that exposes this view. However, these campaigns (connecting the evolving accretion inflow and jet outflow) have been achieved rarely. We request triggered 864ks observations by AstroSat of a BHXB as it transitions from the hard to the soft state, when the accretion disk and relativistic jets change significantly. We have submitted three proposals (A05_130/A05_129/A05_126), but ask to observe only one BHXB (out of 15 listed targets); we ask that these proposals are treated together, distributing the proposal as 624/192/48ks against Indian/International/Canadian stare-time allocations. Our group is well suited to attain the simultaneous multiwavelength observations that will maximize the scientific legacy of these observations; we will also make AstroSat data immediately public and have open procedures for joining our team.

Black hole X-ray binaries (BHXBs) cycle through different accretion states rapidly, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous multi-wavelength observations are the optimal tool that exposes this view. However, these campaigns (connecting the evolving accretion inflow and jet outflow) have been achieved rarely. We request triggered 864ks observations by AstroSat of a BHXB as it transitions from the hard to the soft state, when the accretion disk and relativistic jets change significantly. We have submitted three proposals (A05_130/A05_129/A05_126), but ask to observe only one BHXB (out of 15 listed targets); we ask that these proposals are treated together, distributing the proposal as 624/192/48ks against Indian/International/Canadian stare-time allocations. Our group is well suited to attain the simultaneous multiwavelength observations that will maximize the scientific legacy of these observations; we will also make AstroSat data immediately public and have open procedures for joining our team.

Black hole X-ray binaries (BHXBs) cycle through different accretion states rapidly, providing a time-resolved view of how matter behaves in a strong gravity environment. Simultaneous multi-wavelength observations are the optimal tool that exposes this view. However, these campaigns (connecting the evolving accretion inflow and jet outflow) have been achieved rarely. We request triggered 864ks observations by AstroSat of a BHXB as it transitions from the hard to the soft state, when the accretion disk and relativistic jets change significantly. We have submitted three proposals (A05_130/A05_129/A05_126), but ask to observe only one BHXB (out of 15 listed targets); we ask that these proposals are treated together, distributing the proposal as 624/192/48ks against Indian/International/Canadian stare-time allocations. Our group is well suited to attain the simultaneous multiwavelength observations that will maximize the scientific legacy of these observations; we will also make AstroSat data immediately public and have open procedures for joining our team.

Swift J1749.4–2807 is an eclipsing accreting millisecond X-ray pulsar (AMXP) having tight constraints on its inclination range (˜ 74.4 - 77.3 degree ). It is a unique AMXP that shows double peaked pulse profiles during its outbursts and most importantly, it shows uncommonly strong harmonic content that, together with the known inclination, suggests that it might be the best source to date to set constraints on neutron star properties including compactness and geometry. To further explore this possibility we propose to observe the next outburst of Swift J1749.4–2807 with 40 ksec. We aim at performing pulse profile evolution study and to model these pulse profiles to constrain Equation of State (EOS) models. We will also perform spectral study of this source using X-ray data of the AstroSat (SXT+LAXPC). This will be complemented by an extensive Swift monitoring of the new outburst.

We planned to investigate and verify decay trend of the cyclotron line energy of Vela X-1 using Astrosat measurements with high accuracy. We would also derive spectrum covering wide-energy band from 0.3-150 keV energy and study light-curves in X-rays and their correlation. We, therefore, propose Astrosat observation for a net exposure of 40 k-seconds using LAXPCs as prime instrument. The data from SXT, CZTI would also be utilised to compliment multi-wavelength studies.

In recent, very successful coordinated multiwavelength campaigns on several Galactic black hole X-ray binaries, we have detected fast sub-second optical and infrared variability and remarkable multiwavelength timing correlations. These rule out a reprocessing origin for the optical fluxes. Instead, the data support a scenario where the rapid optical variations arise at the jet base, thereby allowing fundamental, quantitative constraints on the extensions of relativistic jets in compact objects. But such constraints exist for less than a handful of objects. Here, we propose to extend such constraints with anticipated ToO observations of up to 2 hard state outbursts with AstroSat strictly simultaneous with ground-based optical/infrared timing. We will probe rapid, sub-second photometric variations and search for inter-band time delays to disentangle the jet/disc/coronal components using spectral-timing. We additionally propose to test and calibrate UVIT timing mode.

In recent, very successful coordinated multiwavelength campaigns on several Galactic black hole X-ray binaries, we have detected fast sub-second optical and infrared variability and remarkable multiwavelength timing correlations. These rule out a reprocessing origin for the optical fluxes. Instead, the data support a scenario where the rapid optical variations arise at the jet base, thereby allowing fundamental, quantitative constraints on the extensions of relativistic jets in compact objects. But such constraints exist for less than a handful of objects. Here, we propose to extend such constraints with anticipated ToO observations of up to 2 hard state outbursts with AstroSat strictly simultaneous with ground-based optical/infrared timing. We will probe rapid, sub-second photometric variations and search for inter-band time delays to disentangle the jet/disc/coronal components using spectral-timing. We additionally propose to test and calibrate UVIT timing mode.

We propose a 40 ks observation of 4U 0923-31 using AstroSat to investigate its X-ray properties. 4U 0923-31 is a steady X-ray source, most likely an X-ray binary, discovered by the first X-ray satellite UHURU, but its nature is yet to be understood, with no published literature on this source. From an analysis of RXTE data we get a marginal evidence for a periodicity in this source. The RXTE observations were short (~15 ks) and hence could not confirm the nature of this source. With the proposed AstroSat observation, we should be able to detect possible pulsations in the source using LAXPC and make a detailed spectral study using the broad band coverage of AstroSat SXT and LAXPC. This will enable us to investigate whether this source is an X-ray pulsar or an accreting black hole source.

Recently proposed non-shell burning class of symbiotics posed a challenge for the understanding of their morphology and structure. With no or weak diagnostic lines available in visible as well as variable nature of red giant component dominating in near infrared, the ultra-violet (UV) observations are the most reliable methods to probe these rare objects. We have been allocated UVIT observing time in last AO cycle 4 for single pointing observation to reconstruct spectral energy distribution (SED) of one such object - SU Lyn. Here we propose regular UVIT monitoring observations (once a month) in single NUV silica filter to see the eclipsing effects in UV continuum over the period of 7-8 months. We also propose two pointing observations 6 months apart for Grism spectroscopy to detect any phase related change in FUV spectra of SU Lyn. SXT is requested to be secondary instrument for a plausible UV-X-ray correlation studies.

We plan to map X-ray bright Planetary nebulae (PN) in various FUV and NUV filters that isolate high excitation spectral lines like 1550 A CIV, 1640 A He II and intermediate and low excitation lines like 2326 CII] , 2470 A [O II] etc to study the shocked regions in the nebula (by stellar winds) and their thermal and photoionization structures. These studies are important in obtaining better physical model of the nebula and for the studies of elemental abundances. They also illustrate how stellar wind interactions change the structure of the PNs

We plan to map X-ray bright Planetary nebulae (PN) in various FUV and NUV filters that isolate high excitation spectral lines like 1550 A CIV, 1640 A He II and intermediate and low excitation lines like 2326 CII] , 2470 A [O II] etc to study the shocked regions in the nebula (by stellar winds) and their thermal and photoionization structures. These studies are important in obtaining better physical model of the nebula and for the studies of elemental abundances. They also illustrate how stellar wind interactions change the structure of the PNs

We propose to observe the UV emission from the low luminosity stellar disks of four spiral galaxies that have extended ultraviolet (XUV) disks. Our targets have all been detected by GALEX. They are all nearby spirals that we have selected based on their UV luminosity and disk sizes. XUV galaxies show star formation well beyond their optical disks, in halo dominated regions where the disk surface density lies below the threshold for star formation. GALEX found that 30% of spiral galaxies have XUV disks. The star formation is thought to be triggered by gas accretion from nearby clouds, galaxies or the intergalactic medium. In this study we will investigate the nature of XUV disk star formation, estimate its rate and morphology. The high sensitivity of UVIT will help isolate the star forming knots, estimate their colors, ages, star formation rates and sizes.

We propose to observe the UV emission from the low luminosity stellar disks of four spiral galaxies that have extended ultraviolet (XUV) disks. Our targets have all been detected by GALEX. They are all nearby spirals that we have selected based on their UV luminosity and disk sizes. XUV galaxies show star formation well beyond their optical disks, in halo dominated regions where the disk surface density lies below the threshold for star formation. GALEX found that 30% of spiral galaxies have XUV disks. The star formation is thought to be triggered by gas accretion from nearby clouds, galaxies or the intergalactic medium. In this study we will investigate the nature of XUV disk star formation, estimate its rate and morphology. The high sensitivity of UVIT will help isolate the star forming knots, estimate their colors, ages, star formation rates and sizes.

We propose to observe in the direction of four holes in the interstellar medium. These regions have low column densities which make them ideal locations to study the diffuse cosmic ultraviolet background radiation as there is less foreground emission from dust scattered starlight.The source of a substantial component of this observed UV background still remains a mystery.From these observations we will be able to estimate the contribution from dust scattering and extragalactic light from resolved sources to the observed background.Requested observations include two holes each in the northern and southern hemisphere which will give an estimate of whether the extragalactic light is of same magnitude in these directions and also allows us to sample integrated light from resolved sources over a larger area.The exposure time proposed is 20,000 seconds for deeper observations with significant SNRs which will aid in the study of different component contributing to the observed UV background.

This proposal is in continuation of efforts to improve the phase-resolved polarization measurements of Crab pulsar reported in Vadawale et.al., 2018 using CZT-Imager. We reported the most sensitive measurement to date of polarization for Crab with CZT-Imager, when averaged over all phases. Estimated degree of polarization is ~ 32.7% with polarization angle ~143.5¿ . Analysis of polarization fraction and angle as function of pulse phase confirmed the higher polarization fraction in off-pulse and showed and indication of variation of po- larization properties within off-pulse emission. The data also hint at a swing of polarization angles across pulse peaks. However, in order to draw concrete conclusions from observations regarding emission mod- els and geometry, higher significance is required. Hence, we propose to continue the observation of Crab with AstroSat to achieve this over the mission life time. We propose 300 ks of observation during this cycle.

Blazars dominates the extra galactic sky in gamma-ray. The physical mechanism behind the high energy gamma-ray emission is still unknown. Multi-wavelength SED shows two characteristic broad humps, one in IR to X-ray and other in X-ray to gamma-ray band. We propose 60 ks observations each of CTA 102 and PKS 1222+216(4C +21.35), total observations is 120 ks. These sources have shown the minute scale variability in gamma-ray energies (Shukla et al. 2018; Aleksic et al. 2011), which challenges the existing standard emission models of blazars. Since AstroSat have UV, soft and hard X-ray instruments on board, it will be a great opportunity to study the variability in UV and X-ray along with simultaneous observation from Fermi at gamma-ray energies. The simultaneous observations from UVIT, SXT, LAXC and CZTI will be used to study the broad band SED, which will tell us about the physical processes happening in jets of blazars.

Blazars dominates the extra galactic sky in gamma-ray. The physical mechanism behind the high energy gamma-ray emission is still unknown. Multi-wavelength SED shows two characteristic broad humps, one in IR to X-ray and other in X-ray to gamma-ray band. We propose 60 ks observations each of CTA 102 and PKS 1222+216(4C +21.35), total observations is 120 ks. These sources have shown the minute scale variability in gamma-ray energies (Shukla et al. 2018; Aleksic et al. 2011), which challenges the existing standard emission models of blazars. Since AstroSat have UV, soft and hard X-ray instruments on board, it will be a great opportunity to study the variability in UV and X-ray along with simultaneous observation from Fermi at gamma-ray energies. The simultaneous observations from UVIT, SXT, LAXC and CZTI will be used to study the broad band SED, which will tell us about the physical processes happening in jets of blazars.

We request the multi-wavelength ASTROSAT observation of the peculiar blazar 1ES 1741+196, in single pointing for 40 ks observing time. Being hosted in a triplet of interacting galaxies, previous observations of this source leave caveats in understanding the origin of optical/IR emission; that could be either from the host galaxy together with the companion galaxies, and/or from the blazar which could be explained by inhomogeneous curved helical jet models. The UVIT data, together with other archival data of this less-variable source can shed light on the emission features of the blazar and the host galaxy. SXT and LAXPC data will be helpful in constraining the synchrotron peak of the source, which was not feasible in the previous X-ray observations. Since the source is less variable in $\gamma$-rays, the combine ASTROSAT and the Fermi /MAGIC/VERITAS observations can provide a better understanding on the non-thermal emission features of this blazar.

We request multi-wavelength AstroSat observations of Swift/BAT-selected, two type 1 Active Galactic Nuclei (AGN). Using AstroSat and ground-based optical telescopes, we plan to derive simultaneous multi-wavelength spectral energy distributions (SEDs), including the far and near UV grating spectra. AstroSat is the only satellite which can provide such multiwavelength data for AGN. We will use these data to (i) model fit the broad band SEDs (and test current theoretical ideas), (ii) derive bolometric luminosity, accretion rate and bolometric correction factor, (iii) study the connection between the disc emission and the shape of the X-ray continua, and (v) investigate any connection between the disk reflection and the thermal emission from the disc. This is continuous of our earlier programme, and we request a 45 ksec exposure with the UVIT for two targets in this cycle.

We request multi-wavelength AstroSat observations of Swift/BAT-selected, two type 1 Active Galactic Nuclei (AGN). Using AstroSat and ground-based optical telescopes, we plan to derive simultaneous multi-wavelength spectral energy distributions (SEDs), including the far and near UV grating spectra. AstroSat is the only satellite which can provide such multiwavelength data for AGN. We will use these data to (i) model fit the broad band SEDs (and test current theoretical ideas), (ii) derive bolometric luminosity, accretion rate and bolometric correction factor, (iii) study the connection between the disc emission and the shape of the X-ray continua, and (v) investigate any connection between the disk reflection and the thermal emission from the disc. This is continuous of our earlier programme, and we request a 45 ksec exposure with the UVIT for two targets in this cycle.

In recent, very successful coordinated multiwavelength campaigns on several Galactic black hole X-ray binaries, we have detected fast sub-second optical and infrared variability and remarkable multiwavelength timing correlations. These rule out a reprocessing origin for the optical fluxes. Instead, the data support a scenario where the rapid optical variations arise at the jet base, thereby allowing fundamental, quantitative constraints on the extensions of relativistic jets in compact objects. But such constraints exist for less than a handful of objects. Here, we propose to extend such constraints with anticipated ToO observations of up to 2 hard state outbursts with AstroSat strictly simultaneous with ground-based optical/infrared timing. We will probe rapid, sub-second photometric variations and search for inter-band time delays to disentangle the jet/disc/coronal components using spectral-timing. We additionally propose to test and calibrate UVIT timing mode.

In recent, very successful coordinated multiwavelength campaigns on several Galactic black hole X-ray binaries, we have detected fast sub-second optical and infrared variability and remarkable multiwavelength timing correlations. These rule out a reprocessing origin for the optical fluxes. Instead, the data support a scenario where the rapid optical variations arise at the jet base, thereby allowing fundamental, quantitative constraints on the extensions of relativistic jets in compact objects. But such constraints exist for less than a handful of objects. Here, we propose to extend such constraints with anticipated ToO observations of up to 2 hard state outbursts with AstroSat strictly simultaneous with ground-based optical/infrared timing. We will probe rapid, sub-second photometric variations and search for inter-band time delays to disentangle the jet/disc/coronal components using spectral-timing. We additionally propose to test and calibrate UVIT timing mode.

In recent, very successful coordinated multiwavelength campaigns on several Galactic black hole X-ray binaries, we have detected fast sub-second optical and infrared variability and remarkable multiwavelength timing correlations. These rule out a reprocessing origin for the optical fluxes. Instead, the data support a scenario where the rapid optical variations arise at the jet base, thereby allowing fundamental, quantitative constraints on the extensions of relativistic jets in compact objects. But such constraints exist for less than a handful of objects. Here, we propose to extend such constraints with anticipated ToO observations of up to 2 hard state outbursts with AstroSat strictly simultaneous with ground-based optical/infrared timing. We will probe rapid, sub-second photometric variations and search for inter-band time delays to disentangle the jet/disc/coronal components using spectral-timing. We additionally propose to test and calibrate UVIT timing mode.

In recent, very successful coordinated multiwavelength campaigns on several Galactic black hole X-ray binaries, we have detected fast sub-second optical and infrared variability and remarkable multiwavelength timing correlations. These rule out a reprocessing origin for the optical fluxes. Instead, the data support a scenario where the rapid optical variations arise at the jet base, thereby allowing fundamental, quantitative constraints on the extensions of relativistic jets in compact objects. But such constraints exist for less than a handful of objects. Here, we propose to extend such constraints with anticipated ToO observations of up to 2 hard state outbursts with AstroSat strictly simultaneous with ground-based optical/infrared timing. We will probe rapid, sub-second photometric variations and search for inter-band time delays to disentangle the jet/disc/coronal components using spectral-timing. We additionally propose to test and calibrate UVIT timing mode.

We propose to image interacting galaxies in three Hickson groups, HCG77, HCG79 and HCG54 with UVIT. Interactions and mergers between galaxies can lead to distortions in their shapes and to enhanced star formation in them. The 1.3$-$1.5 arcsec resolution of the UVIT in nuv and fuv will help us study the tidally induced distortions in their shapes and resolve the star formation regions (SFRs) in them. The FUV-NUV colors combined with photometric colors from ground based observations will lead to the study of metallicities and ages of the star forming regions. Comparison with studies of isolated galaxies will help us quantify the enhancement of the star formation due to interactions. Data from existing Sloan Digital Sky Survey (SDSS) would be used (augmented by further ground based observations). Our observations will provide a much clearer picture of the SFRs compared to archival data from Galex.

The NGC2207/IC2163 system hosts one of the youngest merger-induced starburst galaxies in the nearby Universe, making it an excellent target for catching in action the formation and early evolution of young star clusters. This intense, recent star formation has produced luminous neutron star (NS) and black hole (BH) X-ray binaries (XRBs) at a higher rate per unit star formation rate (SFR) than seen in any other galaxy in the local Universe. This is presumably caused by the very young ages of most of the star-forming regions, as predicted from population synthesis models. We propose multiband UVIT observations to measure the temporal evolution of the XRB formation efficiency from the precise ages of their host star forming regions. This is essential for understanding the gravitational-wave sources and short gamma-ray bursts (GRBs) that succeed XRBs.

We propose a 90 ks observation of galactic micro-quasar GRS 1915+105 on 3rd May 2018. GRS 1915+105 which shows extremely rich and puzzling variability features is the most studied galactic micro-quasar.We would like to do simultaneous Swift, Chandra and Nustar observations to compare energy spectrum in various X-ray classes at different flux level. 3.0-5.0 Hz QPO and milli Hz QPO have been already observes with AstroSat/LAXPC for the first time in rho class of GRS 1915+105. Our proposed 90 ks observation is aimed to study the state evolution, the study of nature of high-frequency QPOs, spectro-temporal features, the spectral evolution of source. As GRS 1915+105 is a highly variable source we expect 90 ks observation of AstroSat may unveil many scientific curiosities.

Multiwavelength observations of a bright and variable high frequency BL Lac type object known as 1H 2354-315 are proposed. The source is embedded in a galaxy and is located towards a group of galaxies forming a wall of a supercluster. The aim of the proposal is to use the wide-band X-ray capability of the AstroSat to characterize the precise spectral shape of X-ray emission and study its intensity variability simultaneously in soft X-rays, hard X-rays, nuv and fuv bands. Modelling the SED would probe the location and nature of acceleration processes in the source. Deep exposure in X-rays help to study the presence of transient absorption towards the X-ray source. Simultaneous deep exposures in the UVIT will map and characterize its host galaxy and the galaxies in its neighbourhood in nuv and fuv bands.

We request a single pointing 30 ks observation of Narrow Line Seyfert 1 galaxy (NLS1) Mkn~478 with SXT as primary instrument, simultaneously with LAXPC and UVIT. Mkn~478 is highly variable source and showed flux variation which is not associated with spectral properties. With the proposed observation, we will be able investigate the short-term variability of the source in the X-ray and UV band. The precise determination of the variation is useful in understanding the origin of UV-optical variability and the relationship between the emission in different bands provides important insights to the nature of the source. The simultaneous multi-wavelength coverage of AstroSat helps to construct the broadband SED of the source and constrain the key parameters such as Eddington ratio $L/L_{Edd}$, UV and X-ray spectral slopes, which is crucial in understanding the observed properties of Mkn~478.

Elliptical galaxies have wide variation in their FUV-NUV color, the cause of which has puzzled astronomers for decades. The FUV-NUV color correlates with Mg2 spectral index but the explanation has been elusive. Solving the puzzle requires a large dataset with both UV imaging and optical spectroscopy with the same spatial resolution and coverage. Previous UV imaging by GALEX has too poor a spatial resolution to match ground-based single-fiber spectrsocopy from SDSS. With the advance of optical integral field spectroscopy providing spatial resolution at 2.5\arcsec\ for nearby galaxies, we urgently need high quality FUV images with similar spatial resolution. Therefore, we propose ASTROSAT/UVIT observations to obtain high resolution FUV images for a pilot sample of 3 ellipticals, complemented with NUV images from Swift, to measure the FUV-NUV color gradients and correlate them with stellar population properties (age, metallicity, chemical abundance) measured from spectroscopy to understand UV color variations among ellipticals.

Elliptical galaxies have wide variation in their FUV-NUV color, the cause of which has puzzled astronomers for decades. The FUV-NUV color correlates with Mg2 spectral index but the explanation has been elusive. Solving the puzzle requires a large dataset with both UV imaging and optical spectroscopy with the same spatial resolution and coverage. Previous UV imaging by GALEX has too poor a spatial resolution to match ground-based single-fiber spectrsocopy from SDSS. With the advance of optical integral field spectroscopy providing spatial resolution at 2.5\arcsec\ for nearby galaxies, we urgently need high quality FUV images with similar spatial resolution. Therefore, we propose ASTROSAT/UVIT observations to obtain high resolution FUV images for a pilot sample of 3 ellipticals, complemented with NUV images from Swift, to measure the FUV-NUV color gradients and correlate them with stellar population properties (age, metallicity, chemical abundance) measured from spectroscopy to understand UV color variations among ellipticals.

Elliptical galaxies have wide variation in their FUV-NUV color, the cause of which has puzzled astronomers for decades. The FUV-NUV color correlates with Mg2 spectral index but the explanation has been elusive. Solving the puzzle requires a large dataset with both UV imaging and optical spectroscopy with the same spatial resolution and coverage. Previous UV imaging by GALEX has too poor a spatial resolution to match ground-based single-fiber spectrsocopy from SDSS. With the advance of optical integral field spectroscopy providing spatial resolution at 2.5\arcsec\ for nearby galaxies, we urgently need high quality FUV images with similar spatial resolution. Therefore, we propose ASTROSAT/UVIT observations to obtain high resolution FUV images for a pilot sample of 3 ellipticals, complemented with NUV images from Swift, to measure the FUV-NUV color gradients and correlate them with stellar population properties (age, metallicity, chemical abundance) measured from spectroscopy to understand UV color variations among ellipticals.

The globular cluster Terzan 5 contains numerous transient low-mass X-ray binaries. At least three of these have undergone X-ray outbursts over the past 15 years, showing a variety of intriguing behaviours. We propose a 40 ks AstroSAT observation of the next bright outburst from Terzan 5, to measure its X-ray energy spectrum, characterize its power spectrum, search for pulsations, and study any X-ray bursts that occur.

Cygnus X-1, the enigmatic black hole binary, has been extensively studied with spectral-timing X-ray observations since the advent of X-ray astronomy. Despite these studies, there are certain aspects of X-ray emission which are not understood well. Different models suggest different origin of hard X-ray emission; some models favour Compton scattering in Corona alone and some predict contribution of Synchrotron emission from the jets. Polarization measurements in X-rays is expected to provide some insights into this aspect. For CZTI on-board AstroSat, which is capable of polarization measurements above 100 keV, Cygnus X-1 is a potential target. Polarization measurements along with broad band spectrum of Cygnus X-1 will be able to put better constraints on the origin of hard X-ray emission. In particular, polarization measurement in hard state of the BHB would be of much interest. In this context, we propose anticipated TOO observation of Cygnus X-1 for 300ks, during hard state.

Our proposal is to search for the elusive Be binary systems with white-dwarf (WD) or subdwarf O-type (sdO) star being the companion to the Be star. Theoretical models suggested that there can be ~10^5 Be-WD and Be-sdO systems in our galaxy. However, no Be-WD system is detected till now and only a few (about 4) binaries were found to belong to Be-sdO category. We identified 8 Be stars in open clusters showing excess in NUV GALEX band. The possible UV excess is suggestive of a WD or sdO companion. However, there are no observation of these sources in the GALEX FUV, which is very much important to characterize the WD/sdO companion. We plan to image these 8 Be stars with UVIT in FUV and NUV filters, thereby characterizing the nature of the ‘invisible’ hot companion.

Our proposal is to search for the elusive Be binary systems with white-dwarf (WD) or subdwarf O-type (sdO) star being the companion to the Be star. Theoretical models suggested that there can be ~10^5 Be-WD and Be-sdO systems in our galaxy. However, no Be-WD system is detected till now and only a few (about 4) binaries were found to belong to Be-sdO category. We identified 8 Be stars in open clusters showing excess in NUV GALEX band. The possible UV excess is suggestive of a WD or sdO companion. However, there are no observation of these sources in the GALEX FUV, which is very much important to characterize the WD/sdO companion. We plan to image these 8 Be stars with UVIT in FUV and NUV filters, thereby characterizing the nature of the ‘invisible’ hot companion.

The class of TeV emitting blazars is dominated by high frequency BL Lac objects (HBLs). The peak of their synchrotron component lies in the range of FUV to X-rays. Here, we propose to obtain continuous deep {\it AstroSat} pointings of two HBLs: 1ES 0120+340 ({\bf 120 ks}) and 1H 1100-230 ({\bf 140 ks}), which will enable us to explore the spectral curvature in X-rays. The spectral curvature will help us to constrain the underlying particle distribution. The simultaneous deep imaging in NUV and FUV bands will provide us a time-series to extract further information through cross-correlation studies. Further multiwavelength data will help to differentiate between leptonic and hadronic models. The investigations of galaxies and stars in the fuv and nuv fields around the targets, not well studied because of poorer coverage with Galex in survey mode, are secondary scientific goals for this project.

Theoretically, galaxy assembly process is expected to be present in all mass ranges. The signatures of the interactions/assembly process in the scales of dwarf galaxies can be better studied in low-density environment where the effect of nearby massive galaxies are minimal. To understand galaxy interactions in smaller scales and associated star formation, we propose a UV study of four dwarf galaxies, which are found to have undergone and/or on-going interactions with multiple nearby systems, in Lynx-Cancer Void region. From UVIT observations we plan to (i) identify the star forming knots and estimate their age as well as spatial distribution and (ii) trace tidal features around these systems. These metal-poor and gas-rich dwarf systems which resemble systems in high redshift can provide valuable insights to our understanding of the hierarchical galaxy assembly processes.

Theoretically, galaxy assembly process is expected to be present in all mass ranges. The signatures of the interactions/assembly process in the scales of dwarf galaxies can be better studied in low-density environment where the effect of nearby massive galaxies are minimal. To understand galaxy interactions in smaller scales and associated star formation, we propose a UV study of four dwarf galaxies, which are found to have undergone and/or on-going interactions with multiple nearby systems, in Lynx-Cancer Void region. From UVIT observations we plan to (i) identify the star forming knots and estimate their age as well as spatial distribution and (ii) trace tidal features around these systems. These metal-poor and gas-rich dwarf systems which resemble systems in high redshift can provide valuable insights to our understanding of the hierarchical galaxy assembly processes.

We request 35 ks ASTROSAT observations of a highly active star FR Cnc in order to characterize it in X-ray and to study the X-ray rotational modulation. We intended to study the variation of X-ray spectral parameters (e.g. coronal temperature, density) with rotational phase and their correlation with the chromospheric and photospheric activities (cool spots) by performing the rotational phase-resolved X-ray spectroscopy.

We ask for 50 ks of observations of the Vela pulsar with the three X-ray instruments onboard the ASTROSAT. The Vela pulsar was among the first pulsars to be discovered in several energy ranges from the radio to the TeV range because of its brightness. Its non-thermal emission provides constraints on the pulsar models as well as on particle acceleration and emission mechanisms. Yet, no publication of the Vela pulsar exists in hard X-rays, i. e. the major part of the sensitivity range of ASTROSAT LAXPC. Previous measurements have shown a power-law emission up to 8 keV. The proposed observations should help establish for the first time the light curve and the spectrum in hard X-rays. Moreover, we will probe the cut-off in the spectrum if any. In either cases, this will have important implications on pulsar models.

We propose a 70-ks ASTROSAT observation of the fastest accreting millisecond pulsar IGR J00291+5934 during its next outburst. We aim at measuring the spin and orbital parameters of this interesting source, in order to improve its ephemeris. This is the only accreting millisecond pulsar for which there is a general agreement on the spin-up observed during outbursts. It also shows a long-term spin-down, probably caused by magnetic dipole emission during quiescent periods or gravitational radiation from the fast spinning neutron star. The next outburst will allow us to constrain the still elusive orbital period derivative in this systems, and its long-term orbital evolution, or to give very tight upper limits. The knowledge of accurate and precise ephemeris of the pulsar are of paramount importance for a meaningful search of the radio and gamma-ray counterparts expected to turn on if the source switches to a rotation-powered pulsar state during X-ray quiescence.

In recent, very successful coordinated multiwavelength campaigns on several Galactic black hole X-ray binaries, we have detected fast sub-second optical and infrared variability and remarkable multiwavelength timing correlations. These rule out a reprocessing origin for the optical fluxes. Instead, the data support a scenario where the rapid optical variations arise at the jet base, thereby allowing fundamental, quantitative constraints on the extensions of relativistic jets in compact objects. But such constraints exist for less than a handful of objects. Here, we propose to extend such constraints with anticipated ToO observations of up to 2 hard state outbursts with AstroSat strictly simultaneous with ground-based optical/infrared timing. We will probe rapid, sub-second photometric variations and search for inter-band time delays to disentangle the jet/disc/coronal components using spectral-timing. We additionally propose to test and calibrate UVIT timing mode.

In recent, very successful coordinated multiwavelength campaigns on several Galactic black hole X-ray binaries, we have detected fast sub-second optical and infrared variability and remarkable multiwavelength timing correlations. These rule out a reprocessing origin for the optical fluxes. Instead, the data support a scenario where the rapid optical variations arise at the jet base, thereby allowing fundamental, quantitative constraints on the extensions of relativistic jets in compact objects. But such constraints exist for less than a handful of objects. Here, we propose to extend such constraints with anticipated ToO observations of up to 2 hard state outbursts with AstroSat strictly simultaneous with ground-based optical/infrared timing. We will probe rapid, sub-second photometric variations and search for inter-band time delays to disentangle the jet/disc/coronal components using spectral-timing. We additionally propose to test and calibrate UVIT timing mode.

In recent, very successful coordinated multiwavelength campaigns on several Galactic black hole X-ray binaries, we have detected fast sub-second optical and infrared variability and remarkable multiwavelength timing correlations. These rule out a reprocessing origin for the optical fluxes. Instead, the data support a scenario where the rapid optical variations arise at the jet base, thereby allowing fundamental, quantitative constraints on the extensions of relativistic jets in compact objects. But such constraints exist for less than a handful of objects. Here, we propose to extend such constraints with anticipated ToO observations of up to 2 hard state outbursts with AstroSat strictly simultaneous with ground-based optical/infrared timing. We will probe rapid, sub-second photometric variations and search for inter-band time delays to disentangle the jet/disc/coronal components using spectral-timing. We additionally propose to test and calibrate UVIT timing mode.

In recent, very successful coordinated multiwavelength campaigns on several Galactic black hole X-ray binaries, we have detected fast sub-second optical and infrared variability and remarkable multiwavelength timing correlations. These rule out a reprocessing origin for the optical fluxes. Instead, the data support a scenario where the rapid optical variations arise at the jet base, thereby allowing fundamental, quantitative constraints on the extensions of relativistic jets in compact objects. But such constraints exist for less than a handful of objects. Here, we propose to extend such constraints with anticipated ToO observations of up to 2 hard state outbursts with AstroSat strictly simultaneous with ground-based optical/infrared timing. We will probe rapid, sub-second photometric variations and search for inter-band time delays to disentangle the jet/disc/coronal components using spectral-timing. We additionally propose to test and calibrate UVIT timing mode.

Requested observation: We propose for a regular-pointing program to study the host galaxies of Tidal Disruption Events (TDEs), distributed within redshift 0.1 using ASTROSAT/UVIT instrument. Total requested time to observe 4 objects using UVIT is 15 ks. Context: Recent developments in ‘Time domain Astronomy’ have discovered several new kinds of luminous transients near the center of galaxies. The diversities in the behavior of these nuclear transients are yet not well explained. The natures of their hosts can shed light on the diversity of nuclear transients. Objectives & Expected scientific results: These observations will lead to determine several physical parameters (e.g., stellar mass, dust content, Star Formation History, Black Hole mass) of the host galaxy. This study will constrain the TDE models and will also help to understand the diverse properties of nuclear transients.

Requested observation: We propose for a regular-pointing program to study the host galaxies of Tidal Disruption Events (TDEs), distributed within redshift 0.1 using ASTROSAT/UVIT instrument. Total requested time to observe 4 objects using UVIT is 15 ks. Context: Recent developments in ‘Time domain Astronomy’ have discovered several new kinds of luminous transients near the center of galaxies. The diversities in the behavior of these nuclear transients are yet not well explained. The natures of their hosts can shed light on the diversity of nuclear transients. Objectives & Expected scientific results: These observations will lead to determine several physical parameters (e.g., stellar mass, dust content, Star Formation History, Black Hole mass) of the host galaxy. This study will constrain the TDE models and will also help to understand the diverse properties of nuclear transients.

Requested observation: We propose for a regular-pointing program to study the host galaxies of Tidal Disruption Events (TDEs), distributed within redshift 0.1 using ASTROSAT/UVIT instrument. Total requested time to observe 4 objects using UVIT is 15 ks. Context: Recent developments in ‘Time domain Astronomy’ have discovered several new kinds of luminous transients near the center of galaxies. The diversities in the behavior of these nuclear transients are yet not well explained. The natures of their hosts can shed light on the diversity of nuclear transients. Objectives & Expected scientific results: These observations will lead to determine several physical parameters (e.g., stellar mass, dust content, Star Formation History, Black Hole mass) of the host galaxy. This study will constrain the TDE models and will also help to understand the diverse properties of nuclear transients.

Requested observation: We propose for a regular-pointing program to study the host galaxies of Tidal Disruption Events (TDEs), distributed within redshift 0.1 using ASTROSAT/UVIT instrument. Total requested time to observe 4 objects using UVIT is 15 ks. Context: Recent developments in ‘Time domain Astronomy’ have discovered several new kinds of luminous transients near the center of galaxies. The diversities in the behavior of these nuclear transients are yet not well explained. The natures of their hosts can shed light on the diversity of nuclear transients. Objectives & Expected scientific results: These observations will lead to determine several physical parameters (e.g., stellar mass, dust content, Star Formation History, Black Hole mass) of the host galaxy. This study will constrain the TDE models and will also help to understand the diverse properties of nuclear transients.

We request 150 ks for select magnetars in outburst, with observations triggered by $>10$ mCrab {\it{Swift}}-XRT flux. Such a triggered observation would be the first magnetar observed by ASTROSAT. Moreover, simultaneous soft and hard X-ray observations are a rarity for magnetars. The aim is to characterize correlated soft-hard variability and outburst evolution. If the outburst phase is bright enough, spin-phase dependent spectrum (or equivalently, energy-dependent phase-folded light curves) from UV/soft X-rays up $>100$ keV energies may be attainable. This will probe for spectral curvature in the $>50$ keV power-law where QED photon splitting can be influential. If, fortuitously, there are typical magnetar bursts of $10^2-10^3$ Crab flux and $\sim100$ ms duration during the outburst phase, then polarization constraints will be attainable in the $>100$ keV regime. This would enable the first polarization constraints of prompt magnetar flare emission in any band, and herald a significant advance for the pulsar/magnetar community.

We request 150 ks for select magnetars in outburst, with observations triggered by $>10$ mCrab {\it{Swift}}-XRT flux. Such a triggered observation would be the first magnetar observed by ASTROSAT. Moreover, simultaneous soft and hard X-ray observations are a rarity for magnetars. The aim is to characterize correlated soft-hard variability and outburst evolution. If the outburst phase is bright enough, spin-phase dependent spectrum (or equivalently, energy-dependent phase-folded light curves) from UV/soft X-rays up $>100$ keV energies may be attainable. This will probe for spectral curvature in the $>50$ keV power-law where QED photon splitting can be influential. If, fortuitously, there are typical magnetar bursts of $10^2-10^3$ Crab flux and $\sim100$ ms duration during the outburst phase, then polarization constraints will be attainable in the $>100$ keV regime. This would enable the first polarization constraints of prompt magnetar flare emission in any band, and herald a significant advance for the pulsar/magnetar community.

We request 150 ks for select magnetars in outburst, with observations triggered by $>10$ mCrab {\it{Swift}}-XRT flux. Such a triggered observation would be the first magnetar observed by ASTROSAT. Moreover, simultaneous soft and hard X-ray observations are a rarity for magnetars. The aim is to characterize correlated soft-hard variability and outburst evolution. If the outburst phase is bright enough, spin-phase dependent spectrum (or equivalently, energy-dependent phase-folded light curves) from UV/soft X-rays up $>100$ keV energies may be attainable. This will probe for spectral curvature in the $>50$ keV power-law where QED photon splitting can be influential. If, fortuitously, there are typical magnetar bursts of $10^2-10^3$ Crab flux and $\sim100$ ms duration during the outburst phase, then polarization constraints will be attainable in the $>100$ keV regime. This would enable the first polarization constraints of prompt magnetar flare emission in any band, and herald a significant advance for the pulsar/magnetar community.

We request 150 ks for select magnetars in outburst, with observations triggered by $>10$ mCrab {\it{Swift}}-XRT flux. Such a triggered observation would be the first magnetar observed by ASTROSAT. Moreover, simultaneous soft and hard X-ray observations are a rarity for magnetars. The aim is to characterize correlated soft-hard variability and outburst evolution. If the outburst phase is bright enough, spin-phase dependent spectrum (or equivalently, energy-dependent phase-folded light curves) from UV/soft X-rays up $>100$ keV energies may be attainable. This will probe for spectral curvature in the $>50$ keV power-law where QED photon splitting can be influential. If, fortuitously, there are typical magnetar bursts of $10^2-10^3$ Crab flux and $\sim100$ ms duration during the outburst phase, then polarization constraints will be attainable in the $>100$ keV regime. This would enable the first polarization constraints of prompt magnetar flare emission in any band, and herald a significant advance for the pulsar/magnetar community.

We request 150 ks for select magnetars in outburst, with observations triggered by $>10$ mCrab {\it{Swift}}-XRT flux. Such a triggered observation would be the first magnetar observed by ASTROSAT. Moreover, simultaneous soft and hard X-ray observations are a rarity for magnetars. The aim is to characterize correlated soft-hard variability and outburst evolution. If the outburst phase is bright enough, spin-phase dependent spectrum (or equivalently, energy-dependent phase-folded light curves) from UV/soft X-rays up $>100$ keV energies may be attainable. This will probe for spectral curvature in the $>50$ keV power-law where QED photon splitting can be influential. If, fortuitously, there are typical magnetar bursts of $10^2-10^3$ Crab flux and $\sim100$ ms duration during the outburst phase, then polarization constraints will be attainable in the $>100$ keV regime. This would enable the first polarization constraints of prompt magnetar flare emission in any band, and herald a significant advance for the pulsar/magnetar community.

%latex%NGC 2818 was the subject of the first published scientific paper from 2.3 metre Vainu Bappu telescope in 1990 (Surendiranath et~al. 1990). The importance is that the PN NGC 2818 is located in the cluster NGC 2818. NGC 2818 is a bipolar planetary nebula with strong optical lobes that are separated by a dark lane. NGC 2818 has a strong spectrum of H$_2$ lines in the IR suggesting collisionally excited H$_2$ of 850$\pm$50 K (suggesting shocks). Does it have an FUV halo or outer structure that has been excited by UV flourscent emission of H$_2$ similar to other bipolars like NGC 6302 and NGC 2440 (Kameswara Rao et~al. 2018 -preparation). We propose to test this aspect by imaging in FUV BaF2, Sapphire and Silica filters. NUV B4, N2, B13 and B15. Additional interest in this nebula is also to study UV properties of the galactic cluster NGC 2818.

The emission from Active Galactic nuclei (AGN) vary on different timescales throughout the electromagnetic spectrum. The strong optical-UV-X-ray variability in AGN are often inter-connected. We plan to monitor the variability pattern of the Seyfert 1.5 galaxy MCG-2-58-22 by simultaneously observing it with UVIT, SXT and LAXPC through 4 pointings. We have been alloted each pointing to be of 20 ks with SXT as the primary instrument. The observations will enable us to understand the relationship between the UV-X-ray emission mechanisms, and the geometry of the emitting regions. MCG-2-58-22 is one of the brightest Seyferts and it is surprising that for such a bright Seyfert, it is much less observed than the other sources in its class. It has not been observed a lot and has never been monitored over the broad UV-Xray band. Thus its Astrosat observation monitoring will be the 1st for the source.

Swift observations of lags between the X-ray and UV/optical bands in AGN show that most of the UV/optical variability is driven by reprocessing of X-rays by a surrounding disc. However the implied disc sizes are bigger than expected, there is an excess lag in the U-band, possibly from the BLR, and a large excess lag between the X-rays and UV, possibly from scattering obscuration in the inner disc. Disc temperature may explain these discrepancies as a higher temperature leads to a more inflated inner disc and hence more scattering obscuration and a more distant BLR hence larger U-band excess. Cooler discs will be more clumpy and appear bigger. Unfortunately, most AGN observed by Swift have been of similar disc temperature. We, therefore, ask to measure lags in NGC4051, with a hotter disc, to determine whether the temperature is the critical parameter. NGC4051 is perfectly suited to observations with ASTROSAT.

We request ASTROSAT observations of the high energy peaked Bl lac source PKS 0352-686 for a detailed study of its spectral curvature. The synchrotron component peaks at ~ 100 keV keV; however, the source was not detected at very high energy indicating a possible curvature in the gamma-ray spectra. The redshift of z=0.087 suggests the VHE spectral curvature due to absorption by extragalactic background light may not be very significant. The synchrotron component of the source is very prominent with peak at hard X-ray. The lack of soft X-ray spectra in the broadband spectral energy distribution (SED) hamper to identify the exact curvature around the peak. We plan a through study of the X-ray spectral curvature, which in turn can highlight about the diffusive processes in the jet. In addition, a broad band spectral modelling using Fermi will possibly answer the peculiar behaviour of the Compton sub-dominance of the source.

We propose to observe three blazars, namely, 1ES 1959+650, 3C 454.3 and Mrk 421 continuously for 100 ks each with SXT. Using additional archival light curves, we shall precisely determine the X-ray power spectral density (PSD) at hours to years timescales. We shall search for any characteristic timescale (e.g., a break) in the PSD and hence test if such patterns translate from the accretion disk to jet. This work will help put additional constraints on the disk-jet connection in AGN. We have indeed found a break in the PSD using similar observation of Mrk 421 in Cycle AO2. Further observation is crucial to determine if the PSD shape remains constant and to draw stronger conclusions about physical cause of the break. In this cycle we plan to organize simultaneous optical flux and polarization monitoring during the Mrk 421 Astrosat pointing, if granted.

We propose a 60~ksec \emph{AstroSAT} observation with LAXPC (as primary instrument) of eclipsing HMXB pulsar \emph{OAO~1657-415} at its late orbital phases. The evolutionary state of this supergiant X-ray binary depicting high X-ray variability within its orbital period suggest it to be a possible link between supergiant fast X-ray transients and normal HMXBs The of the source X-ray spectra during eclipse and early orbital phases show the presence of inhomogeneously distributed clumps of matter near the pulsar. The search for any cyclotron absorption line-like features in 10-100 keV spectra during low and high intensity phases yielded negative results. However, the observation of the pulsar at late orbital phases when the intensity is relatively high is sparse and less explored. The proposed \emph{AstroSAT} observation would allow us to probe the dense stellar-wind near the pulsar at this phase and will also help identifying the much anticipated cyclotron line near $~36$~keV.

MAXI J0911-655 is a new accreting AMXPs, spinning at 340 Hz in NGC 2808. Since its discovery it is showing an astonishing outburst longer than 760 days, a record for an AMXP, whose outburst usually last 2-3 weeks. We propose a 50ks ASTROSAT observation to be performed with SXT, LAXPC and CZTI simultaneously and aiming to i) detect the pulsation, ii) obtain a precise spin frequency value to infer, for the first time, a direct measurement of the spin increased by the accretion of angular momentum with respect to the observation of 2016 April, iii) investigate the broad-band (0.3-150 keV) spectrum to study the accretion disk properties. Those information have strong scientific return, the presence of the pulsation will constrain the models of magnetic burial under accretion, and the measurement of spin frequency variation will allow to test the accretion mechanism and the role in it of the magnetic field.

Nuclear activity can have an impact on the star formation (SF) properties of the hosts of active galactic nuclei (AGN) via feedback processes. Observationally there are evidences for positive and negative feedback and it is likely that they co-exist. Systematic investigation of the SF properties of AGN hosts on various physical scales (pc to kpc) will allow one to (i) reconcile the two contrasting observations on the feedback processes operating on AGN hosts and (ii) examine the complex interplay between black hole activity and SF in AGN. We therefore propose to carry out a systematic analysis of the SF properties of a sample of AGN on physical scales of hundreds of pc down to the lowest physical extent allowable by the resolution of UVIT. We request for a total of 42 ksec to observe three AGN. This is basically an extension of the proposal submitted in A04.

Nuclear activity can have an impact on the star formation (SF) properties of the hosts of active galactic nuclei (AGN) via feedback processes. Observationally there are evidences for positive and negative feedback and it is likely that they co-exist. Systematic investigation of the SF properties of AGN hosts on various physical scales (pc to kpc) will allow one to (i) reconcile the two contrasting observations on the feedback processes operating on AGN hosts and (ii) examine the complex interplay between black hole activity and SF in AGN. We therefore propose to carry out a systematic analysis of the SF properties of a sample of AGN on physical scales of hundreds of pc down to the lowest physical extent allowable by the resolution of UVIT. We request for a total of 42 ksec to observe three AGN. This is basically an extension of the proposal submitted in A04.

We propose to map stars in the Galactic Halo, in various UVIT filters, in order to spatially map the halo metallicity. Such a study is important for understanding the formation of the Galactic Halo. We will also be surveying other major stellar constituents of the Halo through this survey. UVIT is uniquely suited for this purpose, not only because the strongest metal lines in late type stars occur in UV but also because UVIT filters are designed to sample these lines. Its wide field and spatial resolution are well suited for this purpose and can sample halo on both sides of the plane by the same set of instruments. The proposal has TWO parts: calibrations and survey of the Galactic Halo. In this proposal we would like to observe stars with a range in metallicity, Teff, log g and establish their relationship with various UVIT filter indices.

We propose to map stars in the Galactic Halo, in various UVIT filters, in order to spatially map the halo metallicity. Such a study is important for understanding the formation of the Galactic Halo. We will also be surveying other major stellar constituents of the Halo through this survey. UVIT is uniquely suited for this purpose, not only because the strongest metal lines in late type stars occur in UV but also because UVIT filters are designed to sample these lines. Its wide field and spatial resolution are well suited for this purpose and can sample halo on both sides of the plane by the same set of instruments. The proposal has TWO parts: calibrations and survey of the Galactic Halo. In this proposal we would like to observe stars with a range in metallicity, Teff, log g and establish their relationship with various UVIT filter indices.

We propose to map stars in the Galactic Halo, in various UVIT filters, in order to spatially map the halo metallicity. Such a study is important for understanding the formation of the Galactic Halo. We will also be surveying other major stellar constituents of the Halo through this survey. UVIT is uniquely suited for this purpose, not only because the strongest metal lines in late type stars occur in UV but also because UVIT filters are designed to sample these lines. Its wide field and spatial resolution are well suited for this purpose and can sample halo on both sides of the plane by the same set of instruments. The proposal has TWO parts: calibrations and survey of the Galactic Halo. In this proposal we would like to observe stars with a range in metallicity, Teff, log g and establish their relationship with various UVIT filter indices.

We propose to map stars in the Galactic Halo, in various UVIT filters, in order to spatially map the halo metallicity. Such a study is important for understanding the formation of the Galactic Halo. We will also be surveying other major stellar constituents of the Halo through this survey. UVIT is uniquely suited for this purpose, not only because the strongest metal lines in late type stars occur in UV but also because UVIT filters are designed to sample these lines. Its wide field and spatial resolution are well suited for this purpose and can sample halo on both sides of the plane by the same set of instruments. The proposal has TWO parts: calibrations and survey of the Galactic Halo. In this proposal we would like to observe stars with a range in metallicity, Teff, log g and establish their relationship with various UVIT filter indices.

We propose to map stars in the Galactic Halo, in various UVIT filters, in order to spatially map the halo metallicity. Such a study is important for understanding the formation of the Galactic Halo. We will also be surveying other major stellar constituents of the Halo through this survey. UVIT is uniquely suited for this purpose, not only because the strongest metal lines in late type stars occur in UV but also because UVIT filters are designed to sample these lines. Its wide field and spatial resolution are well suited for this purpose and can sample halo on both sides of the plane by the same set of instruments. The proposal has TWO parts: calibrations and survey of the Galactic Halo. In this proposal we would like to observe stars with a range in metallicity, Teff, log g and establish their relationship with various UVIT filter indices.

We propose to map stars in the Galactic Halo, in various UVIT filters, in order to spatially map the halo metallicity. Such a study is important for understanding the formation of the Galactic Halo. We will also be surveying other major stellar constituents of the Halo through this survey. UVIT is uniquely suited for this purpose, not only because the strongest metal lines in late type stars occur in UV but also because UVIT filters are designed to sample these lines. Its wide field and spatial resolution are well suited for this purpose and can sample halo on both sides of the plane by the same set of instruments. The proposal has TWO parts: calibrations and survey of the Galactic Halo. In this proposal we would like to observe stars with a range in metallicity, Teff, log g and establish their relationship with various UVIT filter indices.

We propose to map stars in the Galactic Halo, in various UVIT filters, in order to spatially map the halo metallicity. Such a study is important for understanding the formation of the Galactic Halo. We will also be surveying other major stellar constituents of the Halo through this survey. UVIT is uniquely suited for this purpose, not only because the strongest metal lines in late type stars occur in UV but also because UVIT filters are designed to sample these lines. Its wide field and spatial resolution are well suited for this purpose and can sample halo on both sides of the plane by the same set of instruments. The proposal has TWO parts: calibrations and survey of the Galactic Halo. In this proposal we would like to observe stars with a range in metallicity, Teff, log g and establish their relationship with various UVIT filter indices.

We propose to map stars in the Galactic Halo, in various UVIT filters, in order to spatially map the halo metallicity. Such a study is important for understanding the formation of the Galactic Halo. We will also be surveying other major stellar constituents of the Halo through this survey. UVIT is uniquely suited for this purpose, not only because the strongest metal lines in late type stars occur in UV but also because UVIT filters are designed to sample these lines. Its wide field and spatial resolution are well suited for this purpose and can sample halo on both sides of the plane by the same set of instruments. The proposal has TWO parts: calibrations and survey of the Galactic Halo. In this proposal we would like to observe stars with a range in metallicity, Teff, log g and establish their relationship with various UVIT filter indices.

We propose to map stars in the Galactic Halo, in various UVIT filters, in order to spatially map the halo metallicity. Such a study is important for understanding the formation of the Galactic Halo. We will also be surveying other major stellar constituents of the Halo through this survey. UVIT is uniquely suited for this purpose, not only because the strongest metal lines in late type stars occur in UV but also because UVIT filters are designed to sample these lines. Its wide field and spatial resolution are well suited for this purpose and can sample halo on both sides of the plane by the same set of instruments. The proposal has TWO parts: calibrations and survey of the Galactic Halo. In this proposal we would like to observe stars with a range in metallicity, Teff, log g and establish their relationship with various UVIT filter indices.

A peculiar characteristic of the nearby AGN M81 is that the central supermassive black hole accretes at the Eddington fraction of $\sim$10$^{-5}$. At such an ultralow accretion rate, the standard accretion disk is assumed to truncate at large radii and the accretion takes place via advection-dominated, hot flow. However, such scenarios cannot satisfactorily answer `What is the origin of UV emissions and variability in these systems? Is it the jet base or reprocessing from the truncated disk?'' With the proposed UV/X-ray simultaneous monitoring of M81 for 50 ks, we can provide answers by measuring the X-ray/UV lag and its nature. A lag timescale of the order of days favors outer disk reprocessing while a lag of ks timescale favors jet origin of UV variability. Therefore, the proposed observation will allow us to test the `jet model'' that assume broadband emission during ultralow accretion is due to the jet alone.