The Ultra-Violet Imaging Telescope (UVIT) is one of the payloads in ASTROSAT, the first Indian Space
Observatory. The UVIT instrument has two 375 mm telescopes: one for the far-ultraviolet (FUV) channel
(1300–1800 Å), and the other for the near-ultraviolet (NUV) channel (2000–3000 Å) and the visible (VIS) channel
(3200–5500 Å). UVIT is primarily designed for simultaneous imaging in the two ultraviolet channels with spatial
resolution better than 1 8, along with provisions for slit-less spectroscopy in the NUV and FUV channels. The
results of in-orbit calibrations of UVIT are presented in this paper.