{
  "bibcode": "2011GCN.12253....1D",
  "body": "V. D'Elia (ASDC), S. D. Barthelmy (GSFC),\nW. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),\nM. M. Chester (PSU), C. Guidorzi (U Ferrara),\nS. T. Holland (CRESST/USRA/GSFC), N. P. M. Kuin (UCL-MSSL),\nC. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC),\nA. Melandri (INAF-OAB), D. M. Palmer (LANL), C. J. Saxton (UCL-MSSL),\nG. Stratta (ASDC), C. A. Swenson (PSU) and T. N. Ukwatta (MSU) report\non behalf of the Swift Team:\n\nAt 19:57:46 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 110807A (trigger=458907).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 278.696, -8.760 which is \n   RA(J2000)  =  18h 34m 47s\n   Dec(J2000) = -08d 45' 35\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve shows a single timebin spike\nstructure with a duration of less than 0.064 sec.  The peak count rate\nwas ~3500 counts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 20:03:13.2 UT, 326.8 seconds after\nthe BAT trigger. Using promptly downlinked data we find an X-ray source\nlocated at RA, Dec 278.71751, -8.76597 which is equivalent to:\n   RA(J2000)  = 18h 34m 52.20s\n   Dec(J2000) = -08d 45' 57.5\"\nwith an uncertainty of 3.7 arcseconds (radius, 90% containment). This\nlocation is 79 arcseconds from the BAT onboard position, within the BAT\nerror circle. This position may be improved as more data are received;\nthe latest position is available at http://www.swift.ac.uk/sper.  We\ncannot determine whether the source is fading at the present time. This\nposition is 6.6 arcseconds from that of a known X-ray source: 2XMM\nJ183452.4-084603 in the XMM-NEWTON XMMSSC catalogue. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata does not constrain the column density. \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 332 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 100% of\nthe XRT 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\nXRT error circle. The list of sources is typically complete to about 18 mag. No\ncorrection has been made for the large, but uncertain extinction expected. \n\nDue to the short, soft nature of the burst, and the proximity\nof the source to the Galactic plane (0.3 degrees) we suggest\nthat this source may be a previously unknown Soft Gamma Repeater. \nVerification of this could come if a second burst is seen or\nthe XRT counterpart shows periodicity. \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": 12253,
  "createdOn": 1312748537000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "GRB 110807A: Swift detection of a burst or a posible new SGR",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 110807A"
}