{
  "bibcode": "2015GCN.18538....1S",
  "body": "E. Sonbas (Adiyaman Univ.), V. D'Elia (ASDC), L. Izzo (URoma/ICRA),\nJ. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA) and\nD. M. Palmer (LANL) report on behalf of the Swift Team:\n\nAt 05:50:30 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 151031A (trigger=662330).  Swift slewed to the burst after\na 6 minute delay due to viewing constraints. \nThe BAT on-board calculated location is \nRA, Dec 83.199, -39.092 which is \n   RA(J2000) = 05h 32m 48s\n   Dec(J2000) = -39d 05' 28\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a single-peaked\nstructure with a duration of about 10 sec.  The peak count rate\nwas ~2500 counts/sec (15-350 keV), at ~2 sec after the trigger. \n\nThe XRT began observing the field at 05:57:43.9 UT, 433.6 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source located at RA, Dec 83.19532, -39.12049 which is equivalent\nto:\n   RA(J2000)  = 05h 32m 46.88s\n   Dec(J2000) = -39d 07' 13.8\"\nwith an uncertainty of 4.1 arcseconds (radius, 90% containment). This\nlocation is 103 arcseconds from the BAT onboard position, within the\nBAT error circle. This position may be improved as more data are\nreceived; the latest position is available at\nhttp://www.swift.ac.uk/sper.  We cannot determine whether the source is\nfading at the present time. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density consistent with the Galactic value of 2.62\nx 10^20 cm^-2 (Willingale et al. 2013). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 439 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 none of\nthe XRT error circle. The 8'x8' region for the list of sources generated\non-board covers 100% of the XRT error circle. The list of sources is typically\ncomplete to about 18 mag. No correction has been made for the expected\nextinction corresponding to E(B-V) of 0.03. \n\nBurst Advocate for this burst is E. Sonbas (edasonbas AT yahoo.com). \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": 18538,
  "createdOn": 1446271617000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 151031A: Swift detection of a burst",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 151031A"
}