{
  "bibcode": "2015GCN.18136....1D",
  "body": "A. D'Ai (INAF-IASFPA), N. Gehrels (NASA/GSFC), A. Y. Lien (GSFC/UMBC),\nF. E. Marshall (NASA/GSFC), A. Maselli (INAF-IASFPA),\nK. L. Page (U Leicester), D. M. Palmer (LANL),\nB. Sbarufatti (INAF-OAB/PSU) and E. Troja (NASA/GSFC/UMCP) report on\nbehalf of the Swift Team:\n\nAt 04:54:28 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated a possible, but unlikely, GRB (trigger=652046). \nSwift slewed immediately to the location. \nThe BAT on-board calculated location is \nRA, Dec 216.661, -7.541 which is \n   RA(J2000) = 14h 26m 39s\n   Dec(J2000) = -07d 32' 27\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a single high\ntime bin with a duration of about 0.128 sec.  The peak count rate\nwas ~1200 counts/sec (15-350 keV), at ~0.1 sec after the trigger. \n\nThe XRT began observing the field at 04:55:25.5 UT, 57.3 seconds after\nthe BAT trigger. No source was detected in 955 s of promptly downlinked\ndata. We are waiting for the full dataset to detect and localise the\nXRT counterpart. \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 60 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 expected extinction corresponding to E(B-V) of\n0.05. \n\nDue to the marginal image significance of this event (6.5 sigma),\nand the lack of an X-ray detection, we believe that this is probably\na statistical fluctuation rather than an astrophysical event. \n\nDetermination of the reality of this event will require the\nfull downlinked dataset.",
  "circularId": 18136,
  "createdOn": 1439443153000,
  "email": "palmer@lanl.gov",
  "subject": "Swift Trigger 652046 is probably not a GRB",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>"
}