{
  "bibcode": "2010GCN.10968....1M",
  "body": "C. B. Markwardt (CRESST/GSFC/UMD), S. D. Barthelmy (GSFC),\nW. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU),\nM. M. Chester (PSU), J. R. Cummings (NASA/UMBC), J. M. Gelbord (PSU),\nS. T. Holland (CRESST/USRA/GSFC), V. Mangano (INAF-IASFPA),\nF. E. Marshall (NASA/GSFC), D. M. Palmer (LANL),\nB. Sbarufatti (INAF-OAB/IASFPA), M. H. Siegel (PSU),\nM. Stamatikos (OSU/NASA/GSFC), C. A. Swenson (PSU),\nE. Troja (NASA/GSFC/ORAU) and T. N. Ukwatta (GSFC/GWU) report on\nbehalf of the Swift Team:\n\nAt 00:42:19 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 100724A (trigger=429868).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is RA, Dec 194.566, -11.121 which is \n   RA(J2000)  =  12h 58m 16s\n   Dec(J2000) = -11d 07' 16\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a double peak structure\nwith a duration of about 70 sec.  The peak count rate\nwas ~3000 counts/sec (15-350 keV), at ~0.5 sec after the trigger. \n\nThe XRT began observing the field at 00:43:48.1 UT, 88.9 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source with an enhanced position: RA, Dec 194.5434, -11.1027\nwhich is equivalent to:\n   RA(J2000)  = 12h 58m 10.41s\n   Dec(J2000) = -11d 06' 09.7\"\nwith an uncertainty of 2.3 arcseconds (radius, 90% containment). This\nlocation is 104 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. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density in excess of the Galactic value (3.35e+20\ncm^-2, Kalberla et al. 2005), with an excess column of 9.7\n(+13.63/-5.98) x 10^20 cm^-2 (90% confidence). \n\nUVOT took a finding chart exposure of nominal 250 seconds with the U filter\nstarting 304 seconds after the BAT trigger. No credible afterglow candidate has\nbeen found in the initial data products. Data from the 2.7'x2.7' sub-image are\nnot available at this time. 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 18.0 mag. No correction has been made for the expected\nextinction corresponding to E(B-V) of 0.04. \n\nBurst Advocate for this burst is C. B. Markwardt (Craig.Markwardt AT nasa.gov). \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": 10968,
  "createdOn": 1279933472000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 100724A: Swift detection of a burst",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 100724A"
}