To facilitate observations of unpredicatbale, sudden astronomical events e.g., outburst of a supernova or nova, observation of a new transient source or X-ray nova, major flars, state transisions in X-ray binaries, etc., AstroSat has a fast turn around observing cycle - the Target of Opportunity (ToO) cycle. Request for ToO observations through a proposal in the ToO cycle must be based on one or more observational evidence(s) (e.g., Astronomy Telegram) of an astronomical event taking place. A ToO proposal is similar to the regular proposals except that the scientific justification for a ToO proposal is short, upto 1000 words maximum, and is free-format. An abstract of length 150 words maximum should also be included in the scientific justification.
The ToO cycle is open for Indian proposers. ToO proposals can be submitted any time through APPS in the ToO cycle. The proposals in this cycle are subjected to fast-track review process by the ToO review committee. 5% AstroSat observing time is reserved for ToO proposals. AstroSat data resulting from a ToO proposal will be made public immediately after the observation and pipeline processing.