Soft X-ray Focusing Telescope Aboard AstroSat: Design, Characteristics and Performance

The Soft X-rayfocusing Telescope (SXT), India’s first X-ray telescopebased on the principle of grazing incidence, was launched aboard the AstroSat and made operational on October 26, 2015. X-raysin the energy band of 0.3–8.0 keV are focussed on to a cooled charge coupled devicethus providing medium resolution X-ray spectroscopyof cosmic X-raysources of various types. It is the most sensitive X-rayinstrument aboard the AstroSat. In its first year of operation, SXT has been used to observe objects ranging from active stars, compact binaries, supernova remnants, active galactic nuclei and clusters of galaxies in order to study its performance and quantify its characteriztics. Here, we present an overview of its design, mechanical hardware, electronics, data modes, observational constraints, pipeline processing and its in-orbit performance based on preliminary results from its characterization during the performance verification phase.