At 17 tons, the observatory is the heaviest unmanned scientific spacecraft ever launched by NASA. Almost twice as heavy as the Hubble Space Telescope, it measures 9 meters (30 feet) long by 4.5 meters (15 feet) in diameter.

The final assembly of the Compton Observatory at the TRW facility

The final assembly of the Compton Observatory at the TRW facility

(Courtesy of NASA)

EGRETEnergetic Gamma Ray Experiment Telescope (EGRET)

EGRET studies the highest-energy gamma rays associated with quasars, neutron stars, and black holes.

COMPTELCompton Telescope (COMPTEL)

COMPTEL is conducting the first deep survey of the entire sky at medium-energy gamma rays. It maps the locations of supernovae and other sources.

OSSEOriented Scintillation Spectrometer Experiment (OSSE)

OSSE measures gamma rays created by matter-antimatter annihilation or by the decay of radioactive elements in energetic solar flares and other celestial sources.

BATSEBurst and Transient Source Experiment (BATSE)

BATSE studies gamma-ray bursts, enigmatic flashes that may come from the most distant part of the observable universe.

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Web Curator: J.D. Myers

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