Abstract:
We have studied the performance of the Ultraviolet Imaging Telescope payload on AstroSat and
derived a calibration of the far-ultraviolet (FUV) and near-ultraviolet (NUV) instruments on
board. We find that the sensitivity of both the FUV and NUV channels is as expected from
ground calibrations, with the FUV effective area about 35 per cent and the NUV effective
area about the same as that of GALEX . The point spread function of the instrument is on
the order of 1.2–1.6. We have found that pixel-to-pixel variations in the sensitivity are less
than 10 per cent with spacecraft motion compensating for most of the flat-field variations. We
derived a distortion correction but recommend that it be applied post-processing as part of an
astrometric solution.
