Small Astronomy Satellite 3

The Small Astronomy Satellite 3 (SAS -C, SAS -3 ) was an X-ray satellite of NASA.

SAS -3 (also known as Explorer 53) was placed in a low equatorial orbit on 7 May 1975, a Scout rocket from the San Marco platform. The satellite was spin-stabilized, but the rotation was also the observation of individual objects to be temporarily stopped. The mission ended in April 1979.

SAS -3 had four different experiments, the X-rays were detected with energies between 0.1 and 60 keV. Special emphasis was placed on good positioning of X-ray sources with an accuracy of about 15 arc seconds, so that they can better identify with known celestial objects can. This made it possible sources are identified with X-ray bursts with narrow double stars and certain X-ray sources are detected as white dwarfs, quasars and nuclei of globular clusters.