{
  "bibcode": "2012GCN.13302....1C",
  "body": "M. M. Chester (PSU), J. R. Cummings (NASA/UMBC), V. D'Elia (ASDC),\nB. Gendre (ASDC), D. M. Palmer (LANL) and G. Stratta (ASDC) report on\nbehalf of the Swift Team:\n\nAt 05:59:42 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 120521A (trigger=522578).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 148.693, -49.419 which is \n   RA(J2000) = 09h 54m 46s\n   Dec(J2000) = -49d 25' 08\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a single short FRED\nstructure with a duration of about 0.7 sec.  The peak count rate\nwas ~5000 counts/sec (15-350 keV), at ~0.25 sec after the trigger. \n\nThe XRT began observing the field at 06:00:56.6 UT, 73.8 seconds after\nthe BAT trigger. Using promptly downlinked data we find a fading,\nuncatalogued X-ray source located at RA, Dec 148.72544, -49.41760 which\nis equivalent to:\n   RA(J2000)  = 09h 54m 54.11s\n   Dec(J2000) = -49d 25' 03.4\"\nwith an uncertainty of 3.7 arcseconds (radius, 90% containment). This\nlocation is 76 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. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density consistent with the Galactic value of 2.08\nx 10^21 cm^-2 (Kalberla et al. 2005). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 77 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.",
  "circularId": 13302,
  "createdOn": 1337580775000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 120521A: Swift detection of a short burst",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 120521A"
}