{
  "bibcode": "2010GCN.11047....1H",
  "body": "E. A. Hoversten (PSU), S. D. Barthelmy (GSFC),\nW. H. Baumgartner (GSFC/UMBC), J. M. Gelbord (PSU), C. Gronwall (PSU),\nS. T. Holland (CRESST/USRA/GSFC), D. M. Palmer (LANL),\nM. H. Siegel (PSU), M. C. Stroh (PSU) and T. N. Ukwatta (GSFC/GWU)\nreport on behalf of the Swift Team:\n\nAt 04:12:42 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 100805A (trigger=430957).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 299.874, +52.614 which is \n   RA(J2000) = 19h 59m 30s\n   Dec(J2000) = +52d 36' 52\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve shows a peak with a\nduration of about 20 sec.  The peak count rate\nwas ~600 counts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 04:14:48.7 UT, 126.4 seconds after\nthe BAT trigger. Using promptly downlinked data we find a fading,\nuncatalogued X-ray source located at RA, Dec 299.87559, 52.62758 which\nis equivalent to:\n   RA(J2000)  = 19h 59m 30.14s\n   Dec(J2000) = +52d 37' 39.3\"\nwith an uncertainty of 3.8 arcseconds (radius, 90% containment). This\nlocation is 47 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\n1.69e+21 cm^-2 (Kalberla et al. 2005). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 129 seconds after the BAT trigger. There is a candidate afterglow in\nthe rapidly available 2.7'x2.7' sub-image at\n  RA(J2000)  =\t19:59:30.52 = 299.87716\n  DEC(J2000) = +52:37:40.3  = 52.62787\nwith a 90%-confidence error radius of about 0.62 arc sec. This position is 3.6\narc sec. from the center of the XRT error circle. The estimated magnitude is\n18.00 with a 1-sigma error of about 0.14. No correction has been made for the\nexpected extinction corresponding to E(B-V) of 0.19. \n\nBurst Advocate for this burst is E. A. Hoversten (hoversten 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": 11047,
  "createdOn": 1280982447000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 100805A: Swift detection of a burst with an optical counterpart",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 100805A"
}