Fabrication and flight performance of a large area balloon borne hard X-ray telescope

Abstract

We describe the fabrication and flight performance of a balloon-borne large area hard X-ray (20–100 keV) telescope for spectral studies of discrete cosmic X-ray sources. The telescope consists of two multi-wire Xenon filled proportional counters of effective area 1200 cm 2 each, mounted on an orientable platform. It can be pre-programmed to track any celestial source with a pointing accuracy of 0.5 degrees. For one hour of observation the telescope has a 5 σ detection sensitivity of 10 −5 ph cm −2 s −1. The laboratory test results and the performance in a series of balloon flights conducted in 1984–1986 period is discussed and the preliminary results obtained for some X-ray sources are presented.