{
  "bibcode": "2010GCN.10317....1V",
  "body": "L. Vetere (PSU), S. D. Barthelmy (GSFC),\nW. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), C. Gronwall (PSU),\nD. Grupe (PSU), S. T. Holland (CRESST/USRA/GSFC),\nE. A. Hoversten (PSU), C. B. Markwardt (CRESST/GSFC/UMD),\nC. Pagani (PSU), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on\nbehalf of the Swift Team:\n\nAt 04:12:49 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 100111A (trigger=382399).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 247.038, +15.557 which is \n   RA(J2000) = 16h 28m 09s\n   Dec(J2000) = +15d 33' 25\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a small precursor\npeak followed by a main FRED peak for a total duration of about 30 sec. \nThe peak count rate was ~3800 counts/sec (15-350 keV), at ~1 sec after\nthe trigger. \n\nThe XRT began observing the field at 04:13:52.1 UT, 63.0 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source located at RA, Dec 247.04766, 15.55090 which is equivalent\nto:\n   RA(J2000)  = 16h 28m 11.44s\n   Dec(J2000) = +15d 33' 03.2\"\nwith an uncertainty of 3.8 arcseconds (radius, 90% containment). This\nlocation is 40 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. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density in excess of the Galactic value (4.09e+20\ncm^-2, Kalberla et al. 2005), with an excess column of 2 (+2.19/-1.28)\nx 10^21 cm^-2 (90% confidence). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 67 seconds after the BAT trigger. There is a candidate afterglow in\nthe rapidly available 2.7'x2.7' sub-image at\n  RA(J2000)  =\t16:28:11.60 = 247.04833\n  DEC(J2000) = +15:33:02.3  = 15.55064\nwith a 90%-confidence error radius of about 0.62 arc sec. This position is 3.4\narc sec. from the center of the XRT error circle. The estimated magnitude is\n17.58 with a 1-sigma error of about 0.14. No correction has been made for the\nexpected extinction corresponding to E(B-V) of 0.05. \n\nBurst Advocate for this burst is L. Vetere (vetere AT astro.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": 10317,
  "createdOn": 1263183869000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 100111A: Swift detection of a burst with an optical afterglow",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 100111A"
}