{
  "bibcode": "2010GCN.11181....1S",
  "body": "T. Sakamoto (NASA/UMBC), W. H. Baumgartner (GSFC/UMBC),\nA. P. Beardmore (U Leicester), J. R. Cummings (NASA/UMBC),\nP. A. Evans (U Leicester), N. Gehrels (NASA/GSFC),\nJ. M. Gelbord (PSU), C. Guidorzi (U Ferrara),\nS. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU),\nW.B Landsman (GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL),\nA. Rowlinson (U Leicester), B. Sbarufatti (INAF-OAB/IASFPA),\nM. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC),\nR. L. C. Starling (U Leicester) and M. C. Stroh (PSU) report on behalf\nof the Swift Team:\n\nAt 19:31:54 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 100902A (trigger=433160).  BAT slewed to the location\nafter a brief delay due to observing constraints. \nThe BAT on-board calculated location is \nRA, Dec 48.646, +30.973 which is \n   RA(J2000) = 03h 14m 35s\n   Dec(J2000) = +30d 58' 21\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a small spike \naround the trigger time.  There are brighter spikes around T+150 sec \nand T+200 sec with a duration of 50 sec.  The peak count rate\nwas ~1200 counts/sec (15-350 keV), at ~210 sec after the trigger. \n\nThe XRT began observing the field at 19:37:10.1 UT, 316.2 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nfading, uncatalogued X-ray source with an enhanced position: RA, Dec\n48.6294, 30.9791 which is equivalent to:\n   RA(J2000)  = 03h 14m 31.05s\n   Dec(J2000) = +30d 58' 44.8\"\nwith an uncertainty of 2.3 arcseconds (radius, 90% containment). This\nlocation is 56 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 in excess of the Galactic value (1.13e+21\ncm^-2, Kalberla et al. 2005), with an excess column of 4.1\n(+2.41/-2.03) x 10^21 cm^-2 (90% confidence). \n\nThe initial flux in the 0.1 s image was 2.20e-07 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of nominal 150 seconds with the\nWhite filter  starting 325 seconds after the BAT trigger. No credible\nafterglow candidate has  been found in the initial data products. Data\nfrom the 2.7'x2.7' sub-image are  not available at this time. The\n8'x8' region for the list of sources  generated on-board covers 100%\nof the XRT error circle. The list of  sources is typically complete to\nabout 18 mag. No correction  has been made for the expected extinction\ncorresponding to E(B-V) of 0.31. \n\nBurst Advocate for this burst is T. Sakamoto (Taka.Sakamoto 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": 11181,
  "createdOn": 1283457096000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 100902A: Swift detection of a burst",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 100902A"
}