{
  "bibcode": "2015GCN.17901....1D",
  "body": "V. D'Elia (ASDC), S. D. Barthelmy (GSFC), J. R. Cummings (NASA/UMBC),\nL. Izzo (URoma/ICRA), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC)\nand M. H. Siegel (PSU) report on behalf of the Swift Team:\n\nAt 03:00:10 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated a possible GRB (trigger=642453).  Swift slewed immediately to \nthe location.  The BAT on-board calculated location is \nRA, Dec 238.343, -46.622 which is \n   RA(J2000) = 15h 53m 22s\n   Dec(J2000) = -46d 37' 19\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  As is usual for an image trigger, there\nis no activity visible in the immediately-available lightcurve. \n\nThe XRT began observing the field at 03:02:28.4 UT, 138.1 seconds after\nthe BAT trigger. No source was detected in 35 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  96 seconds with the White filter\nstarting 141 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\n0.95. \n\nDue to the lack of a rate increase trigger, and the non-detection\nof a counterpart in the relatively short XRT observation, we cannot\nconfirm that this is a real astrophysical source at this time. \nA determination of the reality of this event will require the\nfull downlinked dataset and possibly further XRT observations. \n\nBurst Advocate for this burst is V. D'Elia (delia AT asdc.asi.it). \nPlease contact the BA by email if you require additional information\nregarding Swift followup of this burst. In extremely urgent cases, after\ntrying the Burst Advocate, you can contact the Swift PI by phone (see\nSwift TOO web site for information: http://www.swift.psu.edu/too.html.)",
  "circularId": 17901,
  "createdOn": 1433387899000,
  "email": "palmer@lanl.gov",
  "subject": "Swift Trigger 642453: a possible GRB",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>"
}