{
  "bibcode": "2012GCN.13622....1B",
  "body": "B. N. Barlow (PSU), S. D. Barthelmy (GSFC),\nW. H. Baumgartner (GSFC/UMBC), D. Grupe (PSU),\nF. E. Marshall (NASA/GSFC), D. M. Palmer (LANL) and B.-B. Zhang (PSU)\nreport on behalf of the Swift Team:\n\nAt 15:34:52 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 120811C (trigger=530689).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 199.709, +62.291 which is \n   RA(J2000)  =  13h 18m 50s\n   Dec(J2000) = +62d 17' 29\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve shows a single bright peak\nwith a duration of about 35 sec.  The peak count rate\nwas ~7000 counts/sec (15-350 keV), at ~6 sec after the trigger. \n\nThe XRT began observing the field at 15:36:00.8 UT, 68.7 seconds after\nthe BAT trigger. XRT found a bright, uncatalogued X-ray source located\nat RA, Dec 199.6833, 62.3027 which is equivalent to:\n   RA(J2000)  = +13h 18m 43.99s\n   Dec(J2000) = +62d 18' 09.7\"\nwith an uncertainty of 5.0 arcseconds (radius, 90% containment). This\nlocation is 60 arcseconds from the BAT onboard position, within the BAT\nerror circle. No event data are yet available to determine the column\ndensity using X-ray spectroscopy. \n\nThe initial flux in the 2.5 s image was 2.97e-09 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 75 seconds after the BAT trigger. There is a candidate afterglow in\nthe rapidly available 2.7'x2.7' sub-image at\n  RA(J2000)  =\t13:18:43.81 = 199.68253\n  DEC(J2000) = +62:18:02.7  =  62.30076\nwith a 90%-confidence error radius of about 0.75 arc sec. This position is 7.1\narc sec. from the center of the XRT error circle. The estimated magnitude is\n18.40 with a 1-sigma error of about  0.15. No correction has been made for the\nexpected extinction corresponding to E(B-V) of 0.03. \n\nBurst Advocate for this burst is B. N. Barlow (bnb2 AT 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": 13622,
  "createdOn": 1344700361000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "GRB 120811C: Swift detection of a burst with an optical counterpart",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 120811C"
}