Making of UltraViolet Imaging Telescope

UltraViolet Imaging Telescope (UVIT) is the ultraviolet eye of the first Indian multiwavelength astronomy satellite ASTROSAT. It makes images in near ultraviolet (200 - 300 nm) and far ultraviolet (125-180 nm) with an angular resolution ~1.5" in a field of diameter ~28 arcmin. In each of these channels a smaller bandwidth can be selected by a set of filters mounted on a wheel, and slitless low resolution spectroscopy is also possible in both the channels. Images are also made in a visible channel for tracking drift of the pointing. The drift is used for generation of the final ultraviolet images on ground by adding multiple short exposures with shift and add technique. The instrument is basically a twin telescope with Cassegrain configuration having primary mirrors of ~ 375 mm with intensified CMOS imagers working in photon-counting mode for the ultraviolet channels. In this talk the development of this instrument would be presented with some emphasis on the constraints placed due to nature of such large space projects. The special requirements of a ultraviolet telescope would also be highlighted.