{
  "bibcode": "2011GCN.12020....1D",
  "body": "M. De Pasquale (UCL-MSSL), S. D. Barthelmy (GSFC),\nW. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),\nS. Campana (INAF-OAB), V. D'Elia (ASDC), P. A. Evans (U Leicester),\nS. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU),\nH. A. Krimm (CRESST/GSFC/USRA), N. P. M. Kuin (UCL-MSSL),\nC. B. Markwardt (NASA/GSFC), K. L. Page (U Leicester),\nD. M. Palmer (LANL), T. Sakamoto (NASA/UMBC), C. J. Saxton (UCL-MSSL),\nM. H. Siegel (PSU), C. A. Swenson (PSU) and T. N. Ukwatta (MSU) report\non behalf of the Swift Team:\n\nAt 20:28:48 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 110520A (trigger=453747).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 134.375, +56.402 which is \n   RA(J2000)  =  08h 57m 30s\n   Dec(J2000) = +56d 24' 06\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve shows a FRED-like pulse\nwith a duration of about 30 sec.  The peak count rate\nwas ~2000 counts/sec (15-350 keV), at ~1 sec after the trigger. \n\nThe XRT began observing the field at 20:30:28.3 UT, 100.1 seconds after\nthe BAT trigger. Using promptly downlinked data we find a fading,\nuncatalogued X-ray source located at RA, Dec 134.34208, 56.42720 which\nis equivalent to:\n   RA(J2000)  = 08h 57m 22.10s\n   Dec(J2000) = +56d 25' 37.9\"\nwith an uncertainty of 3.7 arcseconds (radius, 90% containment). This\nlocation is 112 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. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density in excess of the Galactic value (2.73 x\n10^20 cm^-2, Kalberla et al. 2005), with an excess column of 2.5\n(+1.48/-1.31) x 10^21 cm^-2 (90% confidence). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 103 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 M. De Pasquale (mdp AT mssl.ucl.ac.uk). \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": 12020,
  "createdOn": 1305924685000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "GRB 110520A: Swift detection of a burst",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 110520A"
}