{
  "bibcode": "2008GCN..8294....1C",
  "body": "J. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC),\nE. Fenimore (LANL), N. Gehrels (GSFC), C. Guidorzi (INAF-OAB),\nH. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD),\nK. L. Page (U Leicester), D. Palmer (LANL), A. Parsons (GSFC),\nT. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU),\nJ. Tueller (GSFC), T. Ukwatta (GWU)\n(i.e. the Swift-BAT team):\n \nUsing the data set from T-239 to T+323 sec from recent telemetry downlinks,\nwe report further analysis of BAT GRB 080928 (trigger #326115)\n(Sakamoto, et al., GCN Circ. 8292).  The BAT ground-calculated position is\nRA, Dec = 95.063, -55.175 deg, which is \n   RA(J2000)  =  06h 20m 15.1s \n   Dec(J2000) = -55d 10' 29.5\" \nwith an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).\nThe partial coding was 84%.\n \nThe mask-weighted light curve shows that BAT triggered on a weak blip \nthat occurred long before the main emission of this burst.  The initial\npeak started at ~T-10 sec, peaked at ~T_zero, and returned to baseline\naround T+30 sec.  Then a second, slightly larger peak, started at ~T+50\nand ended at ~T+130 sec.  Then the main emission started at ~T+170, with\na pair of peaks at ~T+205 and ~T+215 sec.  We currently only have data\ndownlinked out to T+325 sec and the mask-weighted lightcurve shows\ncontinued emission out to this time.  The flight-generated mask-weighted\nlightcurve (lower resolution) shows no further peaks beyond T+325 sec.\nThe main peak at ~T+210 sec coincides with the peak emission in the\nprompt XRT TDRSS lightcurve.\n \nThe time-averaged spectrum from T+51.1 to T+255.3 sec is best fit by a simple\npower-law model.  The power law index of the time-averaged spectrum is\n1.80 +- 0.12.  The fluence in the 15-150 keV band is 2.1 +- 0.1 x 10^-6 erg/cm2.\nThe 1-sec peak photon flux measured from T+202.83 sec in the 15-150 keV band\nis 2.1 +- 0.1 ph/cm2/sec.  All the quoted errors are at the 90% confidence\nlevel. \n\nWhen we get the remainder of the event-by-event data downlinked,\nwe will issue revised spectral fit results and a T90.\n \nThe results of the batgrbproduct analysis are available at\nhttp://gcn.gsfc.nasa.gov/notices_s/326115/BA/",
  "circularId": 8294,
  "createdOn": 1222643936000,
  "email": "scott@lheamail.gsfc.nasa.gov",
  "subject": "GRB 080928, Swift-BAT initial refined analysis",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>",
  "eventId": "GRB 080928"
}