{
  "bibcode": "2009GCN..8945....1B",
  "body": "S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),\nP. A. Evans (U Leicester), E. E. Fenimore (LANL), N. Gehrels (GSFC),\nH. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL),\nA. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS),\nM. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU)\n(i.e. the Swift-BAT team):\n \nUsing the data set from T-60 to T+303 sec from recent telemetry downlinks,\nwe report further analysis of posible GRB 090307 (trigger #345551)\n(Evans, et al., GCN Circ. 8943).  The BAT ground-calculated position is\nRA, Dec = 245.007, -28.647 deg, which is \n   RA(J2000)  =  16h 20m 01.7s \n   Dec(J2000) = -28d 38' 48.2\" \nwith an uncertainty of 3.3 arcmin, (radius, sys+stat, 90% containment).\nWe note that this position is based on a weak peak in the image domain (5.5 sigma).\nThis is lower than our regular detections because this is a Subthreshold\ntrigger.  The partial coding was 87%.\n \nThe mask-weighted light curve shows a weak pulse starting at ~T-7 sec and\nending at ~T+20 sec.  T90 (15-350 keV) is 22 +- 8 sec (estimated error\nincluding systematics).\n \nThe time-averaged spectrum from T-7.4 to T+16.6 sec is best fit by a simple\npower-law model.  The power law index of the time-averaged spectrum is\n1.08 +- 0.39.  The fluence in the 15-150 keV band is 2.6 +- 0.6 x 10^-7 erg/cm2.\nThe 1-sec peak photon flux measured from T+5.57 sec in the 15-150 keV band\nis 0.2 +- 0.1 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/345551/BA/\n\nGiven the weak nature of this event and the as yet unconfirmed nature\nof this trigger by the XRT follow-up observations, we can not rule out\nthat this trigger is due something other than a GRB.  There are further\nXRT follow-up observations in the observing plan.",
  "circularId": 8945,
  "createdOn": 1236445658000,
  "email": "scott@lheamail.gsfc.nasa.gov",
  "subject": "GRB 090307: Swift-BAT refined analysis of trigger 345551",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>",
  "eventId": "GRB 090307"
}