{
  "bibcode": "2010GCN.11009....1M",
  "body": "D. C. Morris (GWU/GSFC), A. P. Beardmore (U Leicester),\nV. D'Elia (ASDC), P. A. Evans (U Leicester), J. M. Gelbord (PSU),\nC. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC),\nH. A. Krimm (CRESST/GSFC/USRA), O. M. Littlejohns (U Leicester),\nC. B. Markwardt (CRESST/GSFC/UMD), J. P. Osborne (U Leicester),\nC. Pagani (U Leicester), K. L. Page (U Leicester),\nA. Rowlinson (U Leicester), B. Sbarufatti (INAF-OAB/IASFPA),\nM. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC) and\nR. L. C. Starling (U Leicester) report on behalf of the Swift Team:\n\nAt 10:31:55 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 100728B (trigger=430172).  Swift slewed immediately to the \nburst. The BAT on-board calculated location is RA, Dec 44.053, +0.280 \nwhich is\n    RA(J2000) = 02h 56m 13s\n    Dec(J2000) = +00d 16' 46\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including\nsystematic uncertainty).  The BAT light curve showed a single-peaked\nstructure with a duration of about 10 sec plus some possible precursor\nactivity.  The peak count rate was ~2000 counts/sec (15-350 keV),\nat ~0 sec after the trigger.\n\nThe XRT began observing the field at 10:33:32.9 UT, 97.0 seconds after\nthe BAT trigger. No source was detected in the first 2.5 seconds image.\nThe XRT observed the field for approximately 80 seconds in WT mode.\nThe prompt spectrum from the WT data shows evidence of a source.\nDue to an observing constraint no additional PC data were taken to allow\nXRT to centroid on the afterglow and derive a position.\nWe are waiting for the full dataset to detect and localise the\nXRT counterpart.\n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 100 seconds after the BAT trigger. There is a candidate afterglow \nin the rapidly available 2.7'x2.7' sub-image at\n   RA(J2000)  =\t02:56:13.46 = 44.05607\n   DEC(J2000) = +00:16:51.9  =  0.28109\nwith a 90%-confidence error radius of about 0.75 arc sec. This position is \n11.7 arc sec. from the center of the BAT error circle. The estimated \nmagnitude is 17.30 with a 1-sigma error of about 0.14. No correction has \nbeen made for the expected extinction corresponding to E(B-V) of 0.07.\n\nBurst Advocate for this burst is D. C. Morris (david.c.morris AT \nnasa.gov). Please contact the BA by email if you require additional \ninformation regarding Swift followup of this burst. In extremely urgent \ncases, after trying the Burst Advocate, you can contact the Swift PI by \nphone (see Swift TOO web site for information: \nhttp://www.swift.psu.edu/too.html.)",
  "circularId": 11009,
  "createdOn": 1280317360000,
  "email": "kpa@star.le.ac.uk",
  "subject": "GRB 100728B: Swift detection of a burst with an optical counterpart",
  "submitter": "Kim Page at U.of Leicester  <kpa@star.le.ac.uk>",
  "eventId": "GRB 100728B"
}