Compton Gamma Ray Observatory


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Compton Gamma Ray Observatory

(Compton Observatory; CGRO) The second in NASA's series of Great Observatories, launched by the space shuttle Atlantis into a low Earth orbit Apr. 1991. It took its name from the 20th-century US physicist Arthur Holly Compton. Providing nearly six orders of magnitude in spectral coverage, from 15 keV to 30 GeV, it studied a broad range of topics over its nine years of operational life. The 16-tonne observatory contained four gamma-ray telescopes on a stabilized platform.

BATSE, the burst and transient source experiment, measured gamma-ray brightness variations on time scales down to milliseconds; sources included gamma-ray bursts, gamma-ray transients, and solar flares. The instrument consisted of eight identical scintillator-crystal (NaI) detector modules that covered the entire sky, detecting photons in the energy band 0.03–1.9 MeV, plus a smaller spectroscopy detector optimized for broad energy coverage (0.015–110 MeV) and fine energy resolution.

OSSE, the oriented scintillation spectrometer experiment, observed gamma-ray sources in the 0.1–10 MeV range, with a limited capability above 10 MeV. The telescope consisted of four identical detector systems, each articulated to provide a 192° rotation. Normally, two detectors viewed the source, and two a nearby off-source region; the combination was reversed at regular intervals and the difference represented the net source flux.

COMPTEL, the imaging Compton Telescope, carried out a sensitive survey of the entire sky in the range 1–30 MeV. Discrete and extended sky images were reconstructed over a wide field of view with a resolution of the order of 1°.

EGRET, the energetic gamma-ray experiment telescope, covered the range 0.02–20 GeV (approx.). The instrument had an imaging capability at the degree level over a wide field of view. The basic imaging portion consisted of a spark chamber arrangement within a plastic scintillator veto system; imaging was achieved by following the trajectories of the electron-positron pair through the spark chamber to a large NaI scintillation crystal where the photon energy was estimated.

The CGRO was one of the most efficient and successful space telescopes ever launched. It fulfilled its mission almost flawlessly, proving that gamma-ray bursts come from very distant regions of space and are the most powerful explosions in the Universe. In June 2000, NASA scientists deorbited the CGRO, which broke up during a controlled re-entry into the Earth's atmosphere. NASA plans to launch a successor to the CGRO, the Gamma-ray Large Area Space Telescope (GLAST), in 2006.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006
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Bertsch and his colleagues looked for the same periodicity in data from the Compton Gamma Ray Observatory. They found it, clinching the source's identification as a pulsar similar to the ones in the Crab and Vela supernova remnants."
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NASA launches the Compton Gamma Ray Observatory, the second in the Great Observatory series.
In 2000, Nasa engineers successfully directed a safe re-orbit of the 17-ton Compton Gamma Ray Observatory. They used rockets aboard the satellite to bring it down in the Pacific Ocean.
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That chapter addresses additional topics: international cooperation; relations with the human space progra m; the gamma-ray, X-ray, optical, infrared, and radio-astronomy programs; general relativity; the Hubble Space Telescope; the Chandra X-Ray Observatory, formerly known as the Advanced X-Ray Astrophysics Facility (AXAF); the Space Infrared Telescope Facility (SIRTF); the Compton Gamma Ray Observatory (CGRO); and an extrapolation of the future.
The procedures used to measure this distribution from BATSE (the Burst And Transient Source Experiment on NASA's Compton Gamma Ray Observatory) data are discussed.
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The scientific promise of space exploration reached maturity with the results from Hubble, the Cosmic Background Explorer, Hipparcos, Compton Gamma Ray Observatory, and their siblings.
On the other hand, the Compton Gamma Ray Observatory (GRO) bears little resemblance to any of the other space telescope facilities.