  We have studied the performance of the Ultraviolet Imaging Telescope payload
on AstroSat and derived a calibration of the FUV and 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% 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 arcsec. We have found that
pixel-to-pixel variations in the sensitivity are less than 10% 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.
