Soft and medium energy X-rays in the energy range of 0.3-8.0 keV sample the brightest and the richest part of X-ray spectrum of cosmic X-ray sources. X-rays in this energy range are amenable to focusing techniques which leads to (a) nearly 1000 times better sensitivity over non-focusing instruments of similar areas making over 100,000 sources detectable, (b) separation of confusing sources,(c) imaging, (d) spatially resolved spectroscopy, and (e) variability studies.
A low and medium energy X-ray imaging telescope is, therefore, proposed to be built for ASTROSAT.
The telescope to be made from nested gold coated aluminium surfaces will have a focal length of 2 metres and an X-ray CCD as the detector at its focal plane. The soft X-ray payload will cover an energy range of 0.3 to 8.0 keV and provide an energy resolution of 2% at 6 keV for a good quality spectroscopy.