{
  "bibcode": "2015GCN.18223....1B",
  "body": "S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC),\nH. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),\nF. E. Marshall (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU),\nM. Stamatikos (OSU), T. N. Ukwatta (LANL)\n(i.e. the Swift-BAT team):\n \nUsing the data set from T-239 to T+963 sec from the recent telemetry downlink,\nwe report further analysis of BAT GRB 150831B (trigger #653978)\n(Marshall et al., GCN Circ. 18215).  The BAT ground-calculated position is\nRA, Dec = 271.030, -27.243 deg, which is \n   RA(J2000)  =  18h 04m 07.2s \n   Dec(J2000) = -27d 14' 34.4\" \nwith an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).\nThe partial coding was 7%.\n \nThe mask-weighted light curve shows two peaks starting at ~T-0.5 sec,\npeaking at ~T+1 sec, and ending at ~T+8 sec.  T90 (15-350 keV)\nis 6.2 +- 1.0 sec (estimated error including systematics).\n \nThe time-averaged spectrum from T-0.58 to T+6.84 sec is best fit by a simple\npower-law model.  The power law index of the time-averaged spectrum is\n1.87 +- 0.19.  The fluence in the 15-150 keV band is 1.4 +- 0.2 x 10^-06 erg/cm2.\nThe 1-sec peak photon flux measured from T-0.15 sec in the 15-150 keV band\nis 6.1 +- 1.1 ph/cm2/sec.  All the quoted errors are at the 90% confidence\nlevel. \n\nIn the BAT energy band, the hardness ratio vs T90 is typical of a GRB origin,\nbut not inconsistant with a galactic origin.  The T90 is too long for a\nmagnetar origin. We also note that the fading in the X-ray band is tyical\nfor a GRB (D'Avanzo, GCN 18222).\n \nThe results of the batgrbproduct analysis are available at\nhttp://gcn.gsfc.nasa.gov/notices_s/653978/BA/",
  "circularId": 18223,
  "createdOn": 1441113660000,
  "email": "scott@lheamail.gsfc.nasa.gov",
  "subject": "GRB 150831B: Swift-BAT refined analysis",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>",
  "eventId": "GRB 150831B"
}