{{Short description|Space telescope intended for ultraviolet and X-ray observation}} {{Infobox spaceflight | name = Orbiting Astronomical Observatory 3 | names_list = OAO-3, Copernicus, OAO-C, Orbiting Astronomical Observatory-C, PL-701D | image = Oao-3.jpg | image_caption = Orbiting Astronomical Observatory 3 in a clean room before launch. | mission_type = Astronomy | operator = NASA, SERC | COSPAR_ID = 1972-065A | SATCAT = | website = | mission_duration = | spacecraft_bus = | manufacturer = | launch_mass = | dry_mass = {{convert|2204|kg}} | power = <!-- watts --> | launch_date = {{start date text|21 August 1972}} UTC | launch_rocket = Atlas SLV-3C Centaur-D | launch_site = Cape Canaveral LC-36B | launch_contractor = | disposal_type = | deactivated = {{end date text|February 1981}} | decay_date = | orbit_reference = Geocentric | orbit_regime = Low Earth | orbit_periapsis = {{convert|713|km}} | orbit_apoapsis = {{convert|724|km}} | orbit_inclination = 35.0 degrees | orbit_period = 99.2 minutes | orbit_epoch = | apsis = gee | insignia = | previous_mission = OAO-2 }} '''Copernicus''' or '''OAO-3''' ('''Orbiting Astronomical Observatory 3'''), also mentioned as '''Orbiting Astronomical Observatory-C''',<ref name=":1" /><ref>{{Cite web |title=OAO 3 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1972-065A |website=NSSDCA Master Catalog}}</ref> was a space telescope intended for ultraviolet and X-ray observation. After its launch, it was named ''Copernicus'' to mark the 500th anniversary of the birth of Nicolaus Copernicus in 1473.
Part of the Orbiting Astronomical Observatory program, it was a collaborative effort between NASA and the UK's Science Research Council (currently known as the Science and Engineering Research Council).<ref>{{Cite web |title=The Copernicus Satellite |url=https://heasarc.gsfc.nasa.gov/docs/copernicus/copernicus.html |access-date=2024-08-18 |website=heasarc.gsfc.nasa.gov}}</ref>
Copernicus collected high-resolution spectra of hundreds of stars, galaxies and planets, remaining in service until February 1981.<ref name=":1">{{Cite news |date=January 5, 1981 |title=Orbiting Astronomical Observatory-C to be terminated |url=https://commons.wikimedia.org/wiki/File:50th_Anniversary_of_NASA%27s_Copernicus_Mission_(SVS14189_-_GN-19810105-2_full).png |work=Goddard News |pages=1 |volume=28}}</ref>
== History == thumb|At 6:28 a.m. EDT on Aug. 21, 1972, Copernicus lifted off from Complex 36B at Cape Canaveral Air Force Station, Florida. The OAO-3 satellite, weighing 2,150 <abbr>kg</abbr>, was launched on August 21, 1972, by an Atlas SLV-3C from Launch Complex 36, Cape Canaveral, Florida.<ref name=":0">{{Cite web |title=OAO 3 (Copernicus) |url=https://space.skyrocket.de/doc_sdat/oao-3.htm |access-date=2024-08-18 |website=Gunter's Space Page |language=en}}</ref>
The mission used a new inertial reference unit that was developed by the Massachusetts Institute of Technology.<ref name="nasa-goddard-feature2" />
Between 1972 and February 1981,<ref name=":0" /> it returned high-resolution spectra of 551 stars along with extensive X-ray observations.<ref>{{Cite web |title=MAST Copernicus |url=https://archive.stsci.edu/copernicus/ |access-date=2024-08-18 |website=archive.stsci.edu}}</ref> Among the significant discoveries made by ''Copernicus'' were the discovery of several long-period pulsars such as X Persei that had rotation times of many minutes instead of the more typical second or less, and confirmation that most of the hydrogen in interstellar gas clouds existed in molecular form.<ref name="nasa-goddard-feature2">{{cite web |last1=Reddy |first1=Francis |date=19 August 2022 |title=50 Years Ago, NASA's Copernicus Set the Bar for Space Astronomy |url=https://www.nasa.gov/feature/goddard/2022/50-years-ago-nasa-s-copernicus-set-the-bar-for-space-astronomy |access-date=7 January 2023 |website=NASA.gov}}</ref>
== Instrumentation == Copernicus carried two instruments:<ref name="nasa-goddard-feature2" />
* an X-ray detector built by University College London's Mullard Space Science Laboratory; * an 80 cm UV telescope built by Princeton University under the supervision of Lyman Spitzer.
== See also ==
* Orbiting Astronomical Observatory * Orbiting Solar Observatory
== References == {{Reflist}}
Category:Ultraviolet telescopes Category:X-ray telescopes Category:Orbiting Astronomical Observatory