Compton Gamma Ray Observatory

Compton Gamma Ray Observatory
	CGRO deployed in 1991
Mission type	Astronomy
Operator	NASA
COSPAR ID	1991-027B
SATCAT no.	21225
Website	cossc.gsfc.nasa.gov
Mission duration	9 years, 2 months
Spacecraft properties
Manufacturer	TRW Inc.
Launch mass	16,329 kilograms (35,999 lb)
Power	2000.0 Watts
Start of mission
Launch date	5 April 1991, 14:22:45 UTC
Rocket	Space Shuttle Atlantis; STS-37
Launch site	Kennedy LC-39B
End of mission
Decay date	4 June 2000, 23:29:55 UTC
Orbital parameters
Reference system	Geocentric
Regime	Low Earth
Eccentricity	0.006998
Perigee altitude	362 kilometres (225 mi)
Apogee altitude	457 kilometres (284 mi)
Inclination	28.4610 degrees
Period	91.59 minutes
RAAN	68.6827 degrees
Epoch	7 April 1991, 18:37:00 UTC
Main Telescopes (Four)
Type	Scintillation detectors
Focal length	Varied by instrument
Collecting area	Varied by instrument
Wavelengths	X-ray to γ-ray, 20 keV – 30 GeV (40 pm – 60 am)
Instruments
	BATSE, OSSE, COMPTEL, EGRET

The Compton Gamma Ray Observatory (CGRO) was a space observatory detecting photons with energies from 20 keV to 30 GeV, in Earth orbit from 1991 to 2000. The observatory featured four main telescopes in one spacecraft, covering X-rays and gamma rays, including various specialized sub-instruments and detectors. Following 14 years of effort, the observatory was launched from Space Shuttle Atlantis during STS-37 on April 5, 1991, and operated until its deorbit on June 4, 2000.^[3] It was deployed in low Earth orbit at 450 km (280 mi) to avoid the Van Allen radiation belt. It was the heaviest astrophysical payload ever flown at that time at 16,300 kilograms (35,900 lb).

Costing $617 million,^[4] the CGRO was part of NASA's "Great Observatories" series, along with the Hubble Space Telescope, the Chandra X-ray Observatory, and the Spitzer Space Telescope.^[5] It was the second of the series to be launched into space, following the Hubble Space Telescope. The CGRO was named after Arthur Compton, an American physicist and former chancellor of Washington University in St. Louis who received the Nobel prize for work involved with gamma-ray physics. CGRO was built by TRW (now Northrop Grumman Aerospace Systems) in Redondo Beach, California. CGRO was an international collaboration and additional contributions came from the European Space Agency and various universities, as well as the U.S. Naval Research Laboratory.

Successors to CGRO include the ESA INTEGRAL spacecraft (launched 2002), NASA's Swift Gamma-Ray Burst Mission (launched 2004), ASI AGILE (satellite) (launched 2007) and NASA's Fermi Gamma-ray Space Telescope (launched 2008); all remain operational as of May 2023.

^ "NASA – NSSDCA – Spacecraft – Details". nssdc.gsfc.nasa.gov. Retrieved 2018-04-30.
^ "NASA – NSSDCA – Spacecraft – Trajectory Details". nssdc.gsfc.nasa.gov. Retrieved 2018-04-30.
^ "Gamma-Ray Astronomy in the Compton Era: The Instruments". Gamma-Ray Astronomy in the Compton Era. NASA/ GSFC. Archived from the original on 2009-02-24. Retrieved 2007-12-07.
^ Cite error: The named reference sfn2000 was invoked but never defined (see the help page).
^ Barry Logan : MSFC, Kathy Forsythe : MSFC. "NASA – NASA's Great Observatories". www.nasa.gov. Archived from the original on 2011-08-20. Retrieved 2020-11-02.

[1] "NASA – NSSDCA – Spacecraft – Details". nssdc.gsfc.nasa.gov. Retrieved 2018-04-30.

[2] "NASA – NSSDCA – Spacecraft – Trajectory Details". nssdc.gsfc.nasa.gov. Retrieved 2018-04-30.

[3] "Gamma-Ray Astronomy in the Compton Era: The Instruments". Gamma-Ray Astronomy in the Compton Era. NASA/ GSFC. Archived from the original on 2009-02-24. Retrieved 2007-12-07.

[sfn2000-4] Cite error: The named reference sfn2000 was invoked but never defined (see the help page).

[5] Barry Logan : MSFC, Kathy Forsythe : MSFC. "NASA – NASA's Great Observatories". www.nasa.gov. Archived from the original on 2011-08-20. Retrieved 2020-11-02.

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