Editing Compton Gamma Ray Observatory (section)

{{Short description|NASA space observatory designed to detect X-rays and gamma rays (1991–2000)}}
{{Use American English|date=January 2014}}
{{Infobox spaceflight 
| name                  = Compton Gamma Ray Observatory
| image                 = [[File:CGRO s37-96-010.jpg|300px]]
| image_caption         = CGRO deployed in 1991
| insignia              =

| mission_type          = Astronomy 
| operator              = [[NASA]] 
| website               = {{URL|heasarc.gsfc.nasa.gov/docs/cgro/cossc/}}
| COSPAR_ID             = 1991-027B
| SATCAT                = 21225
| mission_duration      = 9&nbsp;years, 2&nbsp;months

| spacecraft_bus        = 
| manufacturer          = [[TRW Inc.]]
| dry_mass              = 
| launch_mass           = {{convert|16329|kg}}
| power                 = 2000.0 Watts<ref>{{Cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1991-027B|title=NASA – NSSDCA – Spacecraft – Details|website=nssdc.gsfc.nasa.gov|access-date=2018-04-30}}</ref>

| launch_date           = {{start date text|5 April 1991, 14:22:45|timezone=yes}}&nbsp;UTC
| launch_rocket         = {{OV|104}}<br />[[STS-37]]
| launch_site           = [[Kennedy Space Center|Kennedy]] [[Kennedy Space Center Launch Complex 39|LC-39B]]
| decay_date            = {{end date text|4 June 2000, 23:29:55}}&nbsp;UTC

| orbit_epoch           = 7 April 1991, 18:37:00&nbsp;UTC<ref>{{Cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1991-027B|title=NASA – NSSDCA – Spacecraft – Trajectory Details|website=nssdc.gsfc.nasa.gov|access-date=2018-04-30}}</ref>
| orbit_reference       = [[geocentric orbit|Geocentric]]
| orbit_regime          = [[low Earth orbit|Low Earth]]
| orbit_periapsis       = {{convert|362|km}}
| orbit_apoapsis        = {{convert|457|km}}
| orbit_eccentricity    = 0.006998
| orbit_inclination     = 28.4610&nbsp;degrees
| orbit_RAAN            = 68.6827&nbsp;degrees
| orbit_period          = 91.59&nbsp;minutes
| apsis                 = gee

| instrument_type       = Telescopes (Four)
| telescope_name        = <!--name, if different to the satellite-->
| telescope_type        = Scintillation detectors
| telescope_diameter    = <!--diameter of telescope-->
| telescope_focal_length= Varied by instrument
| telescope_area        = Varied by instrument
| telescope_wavelength  = [[X-ray]] to [[Gamma ray|γ-ray]], 20&nbsp;[[kiloelectronvolt|keV]] – 30&nbsp;GeV (40&nbsp;[[picometre|pm]] – 60&nbsp;[[atto-|am]])
| telescope_resolution  = <!--resolution of telescope-->

| instruments_list   = {{Infobox spaceflight/Instruments
  |acronym1 = BATSE   |name1 = Burst and Transient Source Experiment
  |acronym2 = OSSE    |name2 = Oriented Scintillation Spectrometer Experiment
  |acronym3 = COMPTEL |name3 = Imaging Compton Telescope
  |acronym4 = EGRET   |name4 = [[Energetic Gamma Ray Experiment Telescope]]
 }}

| programme             = '''[[Great Observatories program|NASA Great Observatories]]'''
| previous_mission      = [[Hubble Space Telescope|Hubble]]
| next_mission          = [[Chandra X-ray Observatory|Chandra]]
| programme2            = '''[[Large Strategic Science Missions]]'''<br><small>''Astrophysics Division''</small>
}}

[[Image:STS-37 Launch.jpg|thumb|right|240px|Launch of  [[Space Shuttle Atlantis|Space Shuttle ''Atlantis'']] carrying the observatory to Earth orbit ([[STS-37]])]]
[[File:NASA image STS37-051-021 Jay Apt on the first EVA of STS-37 with CGRO.jpg|thumb|Astronaut Jay Apt in the Space Shuttle bay with the observatory partially deployed but still attached to the Shuttle's robotic arm]]

The '''Compton Gamma Ray Observatory''' ('''CGRO''') was a [[space observatory]] detecting [[photons]] with [[photon energy|energies]] from 20&nbsp;k[[Electronvolt#Properties|eV]] to 30&nbsp;GeV, in Earth orbit from 1991 to 2000. The observatory featured four main telescopes in one spacecraft, covering [[X-ray]]s and [[gamma ray]]s, including various specialized sub-instruments and detectors. Following 14 years of effort, the observatory was launched from [[Space Shuttle Atlantis|Space Shuttle ''Atlantis'']] during STS-37 on April 5, 1991, and operated until its [[Atmospheric entry#Deorbit disposal|deorbit]] on June 4, 2000.<ref>{{cite web |url=http://heasarc.gsfc.nasa.gov/docs/cgro/epo/brochures/compton/bro5.html |title=Gamma-Ray Astronomy in the Compton Era: The Instruments |access-date=2007-12-07 |work=Gamma-Ray Astronomy in the Compton Era |publisher=NASA/ GSFC |archive-url=https://web.archive.org/web/20090224125500/http://heasarc.gsfc.nasa.gov/docs/cgro/epo/brochures/compton/bro5.html |archive-date=2009-02-24 |url-status=dead }}</ref> It was deployed in [[low Earth orbit]] at {{convert|450|km|mi|abbr=on}} to avoid the [[Van Allen radiation belt]]. It was the heaviest astrophysical payload ever flown at that time at {{convert|16300|kg}}.

Costing $617&nbsp;million,<ref name=sfn2000/> the CGRO was part of [[NASA]]'s [[Great Observatories program|Great Observatories]] series, along with the [[Hubble Space Telescope]], the [[Chandra X-ray Observatory]], and the [[Spitzer Space Telescope]].<ref>{{Cite web|url=https://www.nasa.gov/audience/forstudents/postsecondary/features/F_NASA_Great_Observatories_PS.html|title=NASA – NASA's Great Observatories|first=Kathy Forsythe : MSFC|last=Barry Logan : MSFC|website=www.nasa.gov|access-date=2020-11-02|archive-date=2011-08-20|archive-url=https://web.archive.org/web/20110820072915/http://www.nasa.gov/audience/forstudents/postsecondary/features/F_NASA_Great_Observatories_PS.html|url-status=dead}}</ref> 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 Inc.|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.