Compton Gamma Ray Observatory

The Compton Gamma Ray Observatory (CGRO) was the second of the NASA "Great Observatories" to be launched to space, following the Hubble Space Telescope. CGRO was named after Dr. Arthur Holly Compton (Washington University in St. Louis), Nobel prize winner, for work involved with gamma ray physics. CGRO was built by TRW in Redondo Beach, CA. Following 14 years of effort, the observatory was launched on the Space Shuttle Atlantis, mission STS-37, on 5 April 1991 and operated until its deorbit on 4 June 2000.[1] It was deployed in low earth orbit at 450 km in order to avoid the Van Allen radiation belt. It was the heaviest astrophysical payload ever flown at that time at 17000 kg.
The CGRO is part of NASA's Great Observatories series, with the Hubble Space Telescope, the Chandra X-ray Observatory, and the Spitzer Space Telescope.