{
  "bibcode": "2011GCN.12749....1C",
  "body": "J. R. Cummings (GSFC/UMBC),S. D. Barthelmy (GSFC),\nW. H. Baumgartner (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),\nH. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL),\nT. Sakamoto (GSFC/UMBC), M. Stamatikos (OSU), J. Tueller (GSFC),\nT. N. Ukwatta (MSU) (i.e. the Swift-BAT team):\n\nUsing the data set from T-239 to T+746 sec from the recent telemetry downlink,\nwe report further analysis of BAT GRB 111228A (trigger #510649)\n(Ukwatta, et al., GCN Circ. 12737).  The BAT ground-calculated position is\nRA, Dec = 150.063, 18.284 deg which is\n     RA(J2000)  =  10h 00m 15.0s\n     Dec(J2000) = +18d 17' 02.2\"\nwith an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).\nThe partial coding was 39%.\n\nThe mask-weighted light curve shows multiple peaks in several clusters.  The first\nset of peaks is at a low level from T-12 s to T+12 s.  There is another low level\nset from T+32 to T+42 s, followed by a much brighter set of three overlapping peaks\nfrom T+45 to T+60 s. The final cluster is broad and relatively soft from T+85\nto T+110 s. T90 (15-350 keV) is 101.20 +- 5.42 sec (estimated error including\nsystematics).\n\nThe time-averaged spectrum from T-12.82 to T+115.43 sec is best fit by a simple\npower-law model.  The power law index of the time-averaged spectrum is\n2.27 +- 0.06.  The fluence in the 15-150 keV band is 8.5 +- 0.2 x 10^-6  erg/cm2.\nThe 1-sec peak photon flux measured from T+54.56 sec in the 15-150 keV band\nis 12.4 +- 0.5 ph/cm2/sec.  All the quoted errors are at the 90% confidence\nlevel.\n\nThe results of the batgrbproduct analysis are available at\nhttp://gcn.gsfc.nasa.gov/notices_s/510649/BA/",
  "circularId": 12749,
  "createdOn": 1325121395000,
  "email": "hans.a.krimm@nasa.gov",
  "subject": "GRB 111228A, Swift-BAT refined analysis",
  "submitter": "Hans Krimm at NASA-GSFC  <hans.a.krimm@nasa.gov>",
  "eventId": "GRB 111228A"
}