Editing Neil Gehrels Swift Observatory (section)

== Mission history ==
[[File:Animation of Swift Observatory orbit around Earth.gif|thumb|upright=1.0|left|Animation of Swift Observatory's orbit around Earth, Earth is not shown.]]

Swift was launched on 20 November 2004, at 17:16:01 [[Coordinated Universal Time|UTC]] aboard a [[Delta II]] 7320-10C from [[Cape Canaveral Space Force Station|Cape Canaveral Air Force Station]] and reached a near-perfect orbit of {{cvt|585|xx|604|km}} [[altitude]], with an [[Orbital inclination|inclination]] of 20.60°.<ref name="Trajectory">{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/displayTrajectory.action?id=2004-047A|title=Trajectory: Swift (Explorer 84) 2004-047A|publisher=NASA|access-date=January 14, 2018}} {{PD-notice}}</ref>

On 4 December 2004, an anomaly occurred during instrument activation when the Thermo-Electric Cooler (TEC) Power Supply for the X-Ray Telescope did not turn on as expected. The XRT Team at University of Leicester and Pennsylvania State University were able to determine on 8 December 2004 that the XRT would be usable even without the TEC being operational. Additional testing on 16 December 2004 did not yield any further information as to the cause of the anomaly.

On 17 December 2004 at 07:28:30 UTC, the Swift Burst Alert Telescope (BAT) triggered and located on board an apparent gamma-ray burst during launch and early operations.<ref>{{cite web |url=http://gcn.gsfc.nasa.gov/other/041217.gcn3|title=GRB041217: The First GRB Located On-Board Swift|publisher=NASA|date=December 17, 2004|access-date=May 2, 2009}} {{PD-notice}}</ref> The spacecraft did not autonomously slew to the burst since normal operation had not yet begun, and autonomous slewing was not yet enabled. Swift had its first GRB trigger during a period when the autonomous slewing was enabled on 17 January 2005, at about 12:55 UTC. It pointed the XRT telescope to the on-board computed coordinates and observed a bright X-ray source in the field of view.<ref>{{cite web |url=http://gcn.gsfc.nasa.gov/other/050117.gcn3|title=GRB050117: Swift XRT Position|publisher=NASA|date=January 17, 2005|access-date=July 7, 2015}} {{PD-notice}}</ref>

On 1 February 2005, the mission team released the [[First light (astronomy)|first light]] picture of the UVOT instrument and declared Swift operational.

By May 2010, Swift had detected more than 500 GRBs.<ref>{{cite web|url=http://www.nasa.gov/mission_pages/swift/bursts/500th.html|title=NASA's Swift Catches 500th Gamma-ray Burst|publisher=NASA|date=April 19, 2010|access-date=October 10, 2016}} {{PD-notice}}</ref>

By October 2013, Swift had detected more than 800 GRBs.<ref>{{cite web|url=http://swift.gsfc.nasa.gov/archive/grb_table/stats/|title=Swift GRB Table Stats|publisher=NASA|access-date=November 10, 2013 |archive-url=https://web.archive.org/web/20131110040640/http://swift.gsfc.nasa.gov/archive/grb_table/stats/|archive-date=November 10, 2013}} {{PD-notice}}</ref>

On 27 October 2015, Swift detected its 1,000th GRB, an event named GRB 151027B and located in the constellation [[Eridanus (constellation)|Eridanus]].<ref name="nasa20151106">{{cite web |url=http://www.nasa.gov/feature/goddard/nasas-swift-spots-its-thousandth-gamma-ray-burst|title=NASA's Swift Spots its Thousandth Gamma-ray Burst|publisher=NASA|date=November 6, 2015|access-date=October 10, 2016}} {{PD-notice}}</ref>

On 10 January 2018, NASA announced that the Swift spacecraft had been renamed the Neil Gehrels Swift Observatory in honor of mission PI [[Neil Gehrels]], who died in early 2017.<ref name="spacenews20180111">{{cite news|url=http://spacenews.com/nasa-renames-swift-mission-after-astronomer-neil-gehrels/|title=NASA renames Swift mission after astronomer Neil Gehrels|publisher=SpaceNews |first=Jeff|last=Foust|date=January 11, 2018|access-date=January 13, 2018}}</ref><ref>{{cite news|url=https://www.space.com/39349-swift-observatory-name-change.html|title=NASA Renames Swift Observatory in Honor of Late Principal Investigator|publisher=Space.com|first=Calla|last=Cofield|date=January 10, 2018|access-date=July 10, 2018}}</ref>

Swift entered safe mode on March 15, 2024 (after the 2nd of 4 gyroscopes failed) and was not conducting science. A software patch for two-gyroscope mode was developed, uplinked and tested in April 2024, and Swift returned to nominal operations at that point.<ref>{{Cite web |title=The Neil Gehrels Swift Observatory |url=https://swift.gsfc.nasa.gov/ |access-date=2024-03-22 |website=swift.gsfc.nasa.gov}}</ref>