Editing Neil Gehrels Swift Observatory (section)

{{Short description|NASA satellite of the Explorer program}}
{{Use American English|date=January 2020}}
{{Use dmy dates|date=December 2021}}
{{Infobox spaceflight
| name              = Neil Gehrels Swift Observatory
| names_list        = Explorer-84<br/>MIDEX-3<br/>Swift Gamma Ray Burst Explorer
| image             = Swift Observatory spacecraft model.png
| image_caption     = Neil Gehrels Swift Observatory
| image_size        = 300px

| mission_type      = [[Gamma-ray astronomy]]
| operator          = [[NASA]]{{\}}[[Pennsylvania State University]]
| COSPAR_ID         = 2004-047A
| SATCAT            = 28485
| website           = {{URL|https://swift.gsfc.nasa.gov/}}
| mission_duration  = 2 years (planned)<ref name="4_more_years">{{cite web|url=http://www.omitron.com/headlines/hl05.htm|title=NASA Swift Mission Extended for 4 More Years|publisher=Omitron|access-date=April 7, 2008|archive-url=https://web.archive.org/web/20080408131041/http://www.omitron.com/headlines/hl05.htm|archive-date=April 8, 2008}}</ref> <br/>{{time interval|20 November 2004 17:16|show=ymd|sep=,}} (''in progress'')

| spacecraft        = Explorer LXXXIV
| spacecraft_type   = Swift Gamma Ray Burst Explorer
| spacecraft_bus    = [[Star Bus|LEOStar-3]]
| manufacturer      = [[Spectrum Astro]]
| launch_mass       = {{cvt|1470|kg}}
| dry_mass          = {{cvt|613|kg}}
| payload_mass      = {{cvt|843|kg}}
| dimensions        = {{cvt|5.6|xx|5.4|m}}<ref name="swift-faq">{{cite web|url=http://swift.sonoma.edu/about_swift/general_faq.html|title=Swift Facts and FAQ|publisher=Sonoma State University|date=March 28, 2008|access-date=July 7, 2015|archive-date=24 June 2018|archive-url=https://web.archive.org/web/20180624050438/http://swift.sonoma.edu/about_swift/general_faq.html|url-status=dead}}</ref>
| power             = 1040 [[watt]]s

| launch_date       = 20 November 2004, 17:16:01 [[Coordinated Universal Time|UTC]]
| launch_rocket     = [[Delta II|Delta II 7320-10C]] (Delta 309)
| launch_site       = [[Cape Canaveral Space Force Station|Cape Canaveral]], [[Cape Canaveral Space Launch Complex 17|SLC-17A]]
| launch_contractor = [[Boeing Defense, Space & Security]]<ref name="launchkit2004">{{cite web|url=http://swift.gsfc.nasa.gov/news/2004/swift_presskit.pdf|title=Swift Explorer|publisher=NASA|date=November 1, 2004|access-date=December 18, 2016}} {{PD-notice}}</ref>

| entered_service   = 1 February 2005
| deactivated       = 
| last_contact      = 
| decay_date        =

| orbit_reference   = [[Geocentric orbit]]<ref name="Trajectory"/>
| orbit_regime      = [[Low Earth orbit]]
| orbit_periapsis   = {{cvt|585|km}}
| orbit_apoapsis    = {{cvt|604|km}}
| orbit_inclination = 20.60°
| orbit_period      = 96.60 minutes
| apsis             = gee

| instruments       = Burst Alert Telescope (BAT)<br/>UltraViolet Optical Telescope (UVOT)<br/>X-Ray Telescope (XRT)

| insignia          = Swift Gamma-Ray Burst Mission patch (transparent).png
| insignia_caption  = Swift Gamma Ray Burst Explorer
| insignia_size     = 175px

| programme         = '''Explorer program'''
| previous_mission  = [[GALEX]] (Explorer 83)
| next_mission      = [[THEMIS]] (Explorer 85-89)
}}

'''Neil Gehrels Swift Observatory''', previously called the '''Swift Gamma-Ray Burst Explorer''', is a [[NASA]] three-telescope [[space observatory]] for studying [[gamma-ray burst]]s (GRBs) and monitoring the afterglow in X-ray, and UV/visible light at the location of a burst.<ref name="Display"/> It was launched on 20 November 2004, aboard a [[Delta II]] [[launch vehicle]].<ref name="Trajectory"/> Headed by [[principal investigator]] [[Neil Gehrels]] until his death in February 2017, the mission was developed in a joint partnership between [[Goddard Space Flight Center]] (GSFC) and an international consortium from the United States, United Kingdom, and Italy. The mission is operated by [[Pennsylvania State University]] as part of NASA's [[Explorer program|Medium Explorer program]] (MIDEX).

The burst detection rate is 100 per year, with a sensitivity ~3 times fainter than the BATSE detector aboard the [[Compton Gamma Ray Observatory]]. The Swift mission was launched with a nominal on-orbit lifetime of two years. Swift is a NASA MIDEX (medium-class Explorer) mission. It was the third to be launched, following [[IMAGE (spacecraft)|IMAGE]] and [[Wilkinson Microwave Anisotropy Probe|WMAP]].<ref name="Display">{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2004-047A|title=Display: SWIFT (Explorer 84) 2004-047A|publisher=NASA|date=28 October 2021|access-date=4 December 2021}} {{PD-notice}}</ref>

While originally designed for the study of gamma-ray bursts, Swift now functions as a general-purpose multi-wavelength observatory, particularly for the rapid followup and characterization of astrophysical transients of all types. As of 2020, Swift received 5.5 Target of Opportunity observing proposals per day, and observes ~70 targets per day, on average.<ref>{{cite web |url=https://www.swift.psu.edu/#name|title=Swift Mission Operations Center|publisher=PSU|date=December 27, 2021|access-date=December 27, 2021}} {{PD-notice}}</ref>