{
  "bibcode": "2012GCN.13844....1B",
  "body": "S. D. Barthelmy (GSFC), S. T. Holland (STScI) and J. A. Kennea (PSU)\nreport on behalf of the Swift Team:\n\nAt 02:54:21 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated an outburst from SGR 1806-20 (trigger=535747).  Swift slewed\nimmediately to the source.  The BAT on-board calculated location is \nRA, Dec 272.130, -20.410 which is \n   RA(J2000)  =  18h 08m 31s\n   Dec(J2000) = -20d 24' 35\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve shows a single spike\nwith a duration of about 0.064 sec.  The peak count rate\nwas ~1000 counts/sec (15-350 keV), at ~0.0 sec after the trigger. \n\nThe XRT began observing the field at 02:55:19.9 UT, 58.6 seconds after\nthe BAT trigger. Using promptly downlinked data we find an X-ray source\nwith an enhanced position: RA, Dec 272.1635, -20.4112 which is\nequivalent to:\n   RA(J2000)  = 18h 08m 39.24s\n   Dec(J2000) = -20d 24' 40.3\"\nwith an uncertainty of 4.1 arcseconds (radius, 90% containment). This\nlocation is 113 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. This position is 1.4 arcseconds from that\nof SGR 1806-20. \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 63 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 large, but\nuncertain extinction expected.",
  "circularId": 13844,
  "createdOn": 1349925182000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "Trigger 535747: Swift detection of an outburst from SGR1806-20",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>"
}