The Compton Gamma Ray Observatory

The Compton Gamma Ray Observatory (Compton) was launched aboard the Space Shuttle Atlantis on 5 April 1991, and carried to its 450-km operating orbit. This spacecraft and instruments continue to operate well. The mission provides nearly six orders of magnitude in spectral coverage, from 30 keV to 30 GeV, with a sensitivity over the entire range an order of magnitude better than that of previous observations. The 16000-kg observatory contains four instruments on a stabilized platform. Compton began normal operations on 16 May 1991 and will perform a full-sky survey during its first 18 months of operation. The mission duration is expected to be from six to ten years. A Science Support Center has been established at Goddard Space Flight Center for the purpose of supporting a vigorous Guest Investigator Program. New scientific results to date include: (1) the discovery of intense high-energy (100-MeV) gamma-ray emission from 3C 279; (2) the detection of about one gamma-ray burst per day, including the shortest duration ( approximately 10-ms) burst ever seen; (3) the observation that the smallest gamma-ray bursts are isotropic, calling into question their association with a Galactic population of neutron stars; (4) one of the first images of a gamma-ray burst; and (5) the observation of intense nuclear and positron-annihilation gamma-ray lines and neutrons from several large solar flares.<>