{
  "bibcode": "2012GCN.13934....1D",
  "body": "V. D'Elia (ASDC), S. D. Barthelmy (GSFC),\nW. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU),\nM. M. Chester (PSU), J. R. Cummings (NASA/UMBC),\nN. Gehrels (NASA/GSFC), S. T. Holland (STScI), J. A. Kennea (PSU),\nF. E. Marshall (NASA/GSFC) and D. M. Palmer (LANL) report on behalf of\nthe Swift Team:\n\nAt 22:50:30 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 121031A (trigger=537195).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 170.771, -3.511 which is \n   RA(J2000)  =  11h 23m 05s\n   Dec(J2000) = -03d 30' 37\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve shows a large peak\nwith several smaller peaks riding on top with a total duration\nof about 50 sec.  The peak count rate was ~4000 counts/sec (15-350 keV),\nat ~4 sec after the trigger. \n\nThe XRT began observing the field at 22:51:32.6 UT, 61.9 seconds after\nthe BAT trigger. XRT found a bright, uncatalogued X-ray source located\nat RA, Dec 170.7694, -3.5153 which is equivalent to:\n   RA(J2000)  = +11h 23m 4.66s\n   Dec(J2000) = -03d 30' 55.1\"\nwith an uncertainty of 4.8 arcseconds (radius, 90% containment). This\nlocation is 17 arcseconds from the BAT onboard position, within the BAT\nerror circle. Despite the onboard localisation, no X-ray source was\ndetected in 732 s of promptly-downlinked data, suggesting that the\ninitial centroid may equally have been a cosmic ray. This position\nshould\ttherefore be treated with caution. \n\nThe initial flux in the 2.5 s image was 5.90e-09 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 150 seconds with the White \nfilter starting 70 seconds after the BAT trigger. No aspect solution\nis available for the 2.7'x2.7' sub-image; results from the list of \nsources  generated on-board are not available at this time. The \nexpected extinction corresponding to E(B-V) of 0.05. \n\nWe note that the XRT position is 1.4 arcminutes from the galaxy \n2MASX J11225935-0331287, at redshift 0.1126, which has a nominal \nradius of 0.3 arcminutes according to NED. \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": 13934,
  "createdOn": 1351725424000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 121031A: Swift detection of a burst",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 121031A"
}