{
  "bibcode": "2018GCN.23260....1B",
  "body": "S. D. Barthelmy (GSFC), C. Gronwall (PSU), A. Y. Lien (GSFC/UMBC),\nD. M. Palmer (LANL) and T. Sakamoto (AGU) report on behalf of the Neil\nGehrels Swift Observatory Team:\n\nAt 00:01:30 UT, the Swift Burst Alert Telescope (BAT) triggered on an image\nfluctuation which was misidentified as IGR 17511-3057 (trigger=863053) due to\nincorrect attitude information.  Swift slewed immediately to the target. \nThe BAT on-board calculated location of the image fluctuations is \nRA, Dec 267.574, -31.767, which is \n   RA(J2000)  =  17h 50m 18s\n   Dec(J2000) = -31d 46' 01\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  As is typical for an image trigger, there is nothing\nsignificant in the real-time light curve. \n\nThe XRT began observing the field at 00:16:46.0 UT, 915.7 seconds after\nthe BAT trigger. No source was detected in 305 s of promptly downlinked\ndata. \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 925 seconds after the BAT trigger. No credible afterglow candidate has\nbeen found in the initial data products. The 2.7'x2.7' sub-image covers 25% of\nthe BAT error circle. The typical 3-sigma upper limit has been about 19.6 mag. \nThe 8'x8' region for the list of sources generated on-board covers 100% of the\nBAT error circle. The list of sources is typically complete to about 18 mag. No\ncorrection has been made for the large, but uncertain, extinction expected. \n\nThis event was due to the misidentification of an image fluctuation \nwith a known source, as a result of a known race condition \nin the on-board software.  It is not due to an astrophysical source.",
  "circularId": 23260,
  "createdOn": 1537749054000,
  "email": "palmer@lanl.gov",
  "subject": "Swift Trigger 863053 is not an astrophysical event",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>"
}