  Ultra Violet Imaging Telescope on ASTROSAT Satellite mission is a suite of
Far Ultra Violet (FUV 130 to 180 nm), Near Ultra Violet (NUV 200 to 300 nm) and
Visible band (VIS 320 to 550nm) imagers. ASTROSAT is the first multi wavelength
mission of INDIA. UVIT will image the selected regions of the sky
simultaneously in three channels and observe young stars, galaxies, bright UV
Sources. FOV in each of the 3 channels is about 28 arc-minute. Targeted angular
resolution in the resulting UV images is better than 1.8 arc-second (better
than 2.0 arc-second for the visible channel). Two identical co-aligned
telescopes (T1, T2) of Ritchey-Chretien configuration (Primary mirror of 375 mm
diameter) collect celestial radiation and feed to the detector system via a
selectable filter on a filter wheel mechanism; gratings are available in filter
wheels of FUV and NUV channels for slit-less low resolution spectroscopy. The
detector system for each of the 3 channels is generically identical. One of the
telescopes images in the FUV channel, while the other images in NUV and VIS
channels. Images from VIS channel are also used for measuring drift for
reconstruction of images on ground through shift and add algorithm, and to
reconstruct absolute aspect of the images. Adequate baffling has been provided
for reducing scattered background from the Sun, earth albedo and other bright
objects. One time open-able mechanical cover on each telescope also works as a
Sun-shield after deployment. We are presenting here the overall (mechanical,
optical and electrical) design of the payload.
