CGRO (Compton Gamma-Ray Observatory), one of NASA's Great Observatories, studied the gamma-ray sky using four telescopes that detected different energies. The mission found a class of active galaxies called blazars, mapped the Milky Way’s distribution of a radioactive isotope of aluminum, and hinted at gamma-ray bursts’ cosmological origins, among other discoveries.

past Mission


Space observatory


April 5, 1991


Gamma rays


June 4, 2000

NASA's Compton Gamma Ray Observatory just before release from the space shuttle Atlantis on April 7, 1991, during the STS-37 mission. Compton's successful career ended in June 2000 when the observatory reentered Earth's atmosphere.
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NASA Celebrates 25 Years of Breakthrough Gamma-ray Science

Twenty-five years ago this week, NASA launched the Compton Gamma Ray Observatory, an astronomical satellite that transformed our knowledge of…

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