have observed the same microlensing event. This method was possible because of the large separation between the two spacecraft: Swift is in low Earth orbit while Spitzer is more than one AU distant in an Earth-trailing heliocentric orbit. This separation provided significantly different perspectives of the brown dwarf, allowing for constraints to be placed on some of the object's physical characteristics. 27 October 2015: Swift detected its 1000th gamma-ray burst, GRB 151027B. 18 August 2017: Swift discovers UV emission from the kilonova AT 2017gfo, the electromagnetic counterpart to GW170817. 23 September 2017: Swift is the first to identify as the possible source of the IceCube-170922A extremely high energy (EHE) neutrinos. 14 January 2019: Swift discovers the most powerful observed gamma-ray burst, GRB 190114C, reaching teraelectronvolt energies. See also List of gamma-ray bursts Space Variable Objects Monitor (SVOM), the planned successor of Swift List of X-ray space telescopes GRB 221009A References Further reading External links Swift website by NASA/GSFC Swift website by the UK Swift Science Data Centre Swift website by Pennsylvania State University Swift website by Sonoma State University Gamma-ray Burst Real-time Sky Map Space telescopes Gamma-ray telescopes X-ray telescopes Ultraviolet telescopes Explorers Program Spacecraft launched in 2004 Spacecraft launched by Delta II rockets Articles containing video clips