Extract Light curve

In this tutorial, we will discuss how to extract lightcurves from LAXPC data using the LAXPC software with syntax command:

laxpc_make_lightcurve -p pcu -t timebin - u user_gti_file -e energy_define_file -l Layer_no level2.event.fits

-p flag is used for pcu. The default value is consider as all LAXPC units.
-t flag is for timebin of lightcurve in seconds. The default value is 1.0 seconds
-u flag is for usergti file. This flag is Optional.
-o flag is for output filename. Default output filename is lightcurve.
-e flag is for energy define file: File containing energy ranges. An example file is given. Default file name is ‘eneinput’. If file does not exist, default energy range chosen is a single lighcurve of 3-80 keV.
-l flag is used for Layer no. Which of the five Layers to be considered. Default is all. At this version only a single layer or all can be considered.

If the output root file is the default value of ‘lightcurve’ the following files will be produced:
lightcurve.txt: Ascii text File containing counts/sec with time for the desired energy bands.
lightcurve_Emin_EmaxkeV.lc: Here Emin and Emax are the input energy range.

Here we demonstrate how to extract lightcurve for a black hole X-ray binary source GRS 1915+105 using observation id G06_033T01_9000001116 for orbit 08120. If the flags mentioned above are not specified the values used for the parameters are default values.

$ laxpc_make_lightcurve -u usergti.fits level2.event.fits 
 Event file being used: level2.event.fits                                                                                   
 User Time bin in seconds:    1.0000000000000000     
 PCUs being used: all
 Output file name: lightcurve                                                                                          
 User GTI file name: usergti.fits                                                                                        
 Energy input filename: eneinput                                                                                            
 extracting from all layers 
 start time integer stop time
 No. of energy bins           1
 total no of points in lC=         7833
   0.0000000000000000        7832.0000000000000     
 User start and stop time
   2315.0000000000000        4836.0000000000000     
 No. of segments:         7833           1
 percentage read    100.000000    
 total no of points in lC=         7833
   7832.0000000000000        7832.0000000000000     
 User start and stop time
 No. of segments:         7833        7833

An output file lightcurve_3.0_80.0keV.lc will be created.

$ lcurve
lcurve 1.0 (xronos6.0)
Number of time series for this task[1] 
Ser. 1 filename +options (or @file of filenames +options)[Bkg_Sub_3.0_50.0keV.lc] lightcurve_3.0_80.0keV.lc 
 Series 1 file    1:lightcurve_3.0_80.0keV.lc
WARNING:  Defaulting to first FITS extension
 Selected FITS extensions: 1 - RATE TABLE;
 Source ............ GRS 1915+105        Start Time (d) .... 17841 15:56:33.482
 FITS Extension ....  1 - `lightcurve`   Stop Time (d) ..... 17841 17:17:08.482
 No. of Rows .......         2519        Bin Time (s) ......    1.000
 Right Ascension ...                     Internal time sys.. Converted to TJD
 Declination .......                     Experiment ........ ASTROSAT LAXPC3
 Corrections applied: Vignetting - No ; Deadtime - No ; Bkgd - No ; Clock - No
 Selected Columns:  1- Time;  2- Y-axis;  3- Y-error;
 File contains binned data.
Name of the window file ('-' for default window)[-] 
 Expected Start ... 17841.66427641757  (days)      15:56:33:482  (h:m:s:ms)
 Expected Stop .... 17841.72023706572  (days)      17:17: 8:482  (h:m:s:ms)
 Minimum Newbin Time    1.0000000      (s)
 for Maximum Newbin No..             4835
 Default Newbin Time is:   9.4544388    (s) (to have 1 Intv. of     512 Newbins)
 Type INDEF to accept the default value
Newbin Time or negative rebinning[1] 
 Newbin Time ......     1.0000000      (s)
 Maximum Newbin No.              4835
 Default Newbins per Interval are:         512
 (giving      10 Intervals of          512 Newbins each)
 Type INDEF to accept the default value
Number of Newbins/Interval[7207] 4835
 Maximum of       1 Intvs. with         4835 Newbins of       1.00000     (s)
Name of output file[-] 
Do you want to plot your results?[yes] 
Enter PGPLOT device[/xw] 
    4835 analysis results per interval
WARNING:  Defaulting to first FITS extension
100% completed
 Intv    1   Start 17841 16:35:10
     Ser.1     Avg  3360.        Chisq 0.1143E+06   Var 0.1525E+06 Newbs.   2519
               Min  2449.          Max  4933.    expVar  3360.      Bins   2519

PLT> h lightcurve.ps/ps
PLT> exit