{
  "bibcode": "2011GCN.12720....1S",
  "body": "M. H. Siegel (PSU), W. H. Baumgartner (GSFC/UMBC),\nM. M. Chester (PSU), N. Gehrels (NASA/GSFC), D. Grupe (PSU),\nF. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB),\nD. M. Palmer (LANL), T. Sakamoto (NASA/UMBC), C. A. Swenson (PSU),\nT. N. Ukwatta (MSU) and B.-B. Zhang (PSU) report on behalf of the\nSwift Team:\n\nAt 03:50:37 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 111225A (trigger=510341).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 13.102, +51.589 which is \n   RA(J2000) = 00h 52m 24s\n   Dec(J2000) = +51d 35' 19\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The immediately available lightcurve was\ntruncated for contact with the ground station. The BAT lightcurve showed \na rise at around T-10 seconds with flux continuing at least until\nT+8 seconds, the limit of of the immediately available data.  \nThe peak count rate was ~1300 counts/sec (15-350 keV), at ~-2 sec \nafter the trigger. \n\nThe XRT began observing the field at 03:52:05.9 UT, 88.1 seconds after\nthe BAT trigger. XRT found a bright, uncatalogued X-ray source located\nat RA, Dec 13.1548, 51.5741 which is equivalent to:\n   RA(J2000)  = +00h 52m 37.15s\n   Dec(J2000) = +51d 34' 26.8\"\nwith an uncertainty of 5.0 arcseconds (radius, 90% containment). This\nlocation is 129 arcseconds from the BAT onboard position, within the\nBAT error circle. No event data are yet available to determine the\ncolumn density using X-ray spectroscopy. \n\nThe initial flux in the 2.5 s image was 2.96e-09 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 250 seconds with the U filter starting 95\nseconds after the BAT trigger. There is a candidate afterglow in the rapidly\navailable 2.7'x2.7' sub-image at\n  RA(J2000)  =\t00:52:37.21 =  13.15503\n  DEC(J2000) = +51:34:19.5  =  51.57207\nwith a 90%-confidence error radius of about 0.75 arc sec. This position is 7.3\narc sec. from the center of the XRT error circle. The estimated magnitude is\n19.42 with a 1-sigma error of about  0.20. No correction has been made for the\nexpected extinction corresponding to E(B-V) of 0.26. \n\nBurst Advocate for this burst is M. H. Siegel (siegel AT astro.psu.edu). \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": 12720,
  "createdOn": 1324786346000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 111225A: Swift detection of a burst with an optical counterpart",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 111225A"
}