{
  "bibcode": "2015GCN.17919....1G",
  "body": "N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), D. M. Palmer (LANL) and\nB. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team:\n\nAt 11:41:14 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated a bright source, probably H1743-322, which is currently in \noutburst (Atel #7607; Zhang et al.).  Due to a known race condition\nin the Swift BAT software, this was misidentified as a different location\nwhich corresponds to a different source. \n\nSince the misidentified source has a low catalog threshold, it was\nconsidered unusually bright, triggering a 'Transient Source' response. \nThis included GCN Notices and a Swift follow-up repoint. \n\nThe XRT began observing the field at 12:00:15.4 UT, 1141.1 seconds\nafter the BAT trigger. No source was detected in 997 s of promptly\ndownlinked data. \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 1144 seconds after the BAT trigger. No credible afterglow candidate\nhas been found in the initial data products. The 2.7'x2.7' sub-image covers 25%\nof the BAT error circle. The typical 3-sigma upper limit has been about 19.6\nmag. The 8'x8' region for the list of sources generated on-board covers 100% of\nthe BAT error circle. The list of sources is typically complete to about 18\nmag. No correction has been made for the large, but uncertain extinction\nexpected. \n\nBecause of the software race condition, H1743-322 was not in\nthe XRT FOV after Swift slewed to the incorrect location. \nPreplanned observations of H1743-322 have already been \nmade and more are scheduled.",
  "circularId": 17919,
  "createdOn": 1433938872000,
  "email": "palmer@lanl.gov",
  "subject": "Trigger 643078: Swift detection of H1743-322",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>"
}