X-ray astronomy is a relatively new field because earth’ s atmosphere is opaque to X-rays. The serious studies in this field really began in 1960’ s. Until this time the sun was the first and only celestial object which was an intense source in X-ray waveband. Because of earth’s atmosphere absorbs most of the rays in this waveband, it was needed to examine them above the atmosphere and in the first rocket flight the first extrasolar X-ray source Sco x-1 was detected. After that discovery, the first satellite, Uhuru, which was dedicated to X-ray astronomy was launched. It used two beryllium-window proportional counters with mechanical collimators to map the X-ray sky between 2 and 6 keV as the satellite rotated.[4] Uhuru had a time resolution of 0.1 s and was used to discover the Doppler shifts in the pulse period of Cen X-3 that revealed it as a binary system. The Einstein observatory was launched November 1978. Devamını oku …