The spectral information in the hard X-ray energy region above 30 keV is available only for a small number of X-ray objects even though hard X-ray flux has been observed from about 80 of the 200,000 X-ray sources cataloged ...

The tracking of an astronomical object requires continuous updating of the look angles in azimuth and zenith. The mathematical calculation of these angles needs the position coordinates (latitude and longitude) of the place ...