{
  "bibcode": "2015GCN.17562....1B",
  "body": "W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI),\nN. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC),\nC. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU),\nM. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (LANL)\n(i.e. the Swift-BAT team):\n\nUsing the data set from T-239 to T+471 sec from the recent telemetry downlink,\nwe report further analysis of BAT GRB 150309A (trigger #634200) (Cummings, et\nal., GCN Circ. 17553).  The BAT ground-calculated position is\nRA, Dec = 277.004, 86.417 deg which is\n   RA(J2000)  =  18h 28m 01.0s\n   Dec(J2000) = +86d 25' 02.7\"\nwith an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).\nThe partial coding was 50%.\n\nThe mask-weighted light curve shows that the main peak of the burst, which\noccurred during a Swift preplanned slew maneuver, started at about T-200 seconds.\nThe roughly symmetrical peak with multiple maxima lasted until about T-160\nseconds.  A weaker overlapping peak followed at about T-150 seconds and declined\nto background by about T-60 seconds.  BAT triggered on a smaller peak that lasted\nfrom about T+0 seconds to about T+120 seconds.  T90 (15-350 keV) is\n242 +- 6 sec (estimated error including systematics).  Because the source came\ninto the BAT field of view during the slew, it is possible that there was some\nadditional low-level emission before T-200 seconds.\n\nThe time-averaged spectrum from T-197.32 to T+119.08 sec is best fit by a power\nlaw with an exponential cutoff.  This fit gives a photon index 1.05 +- 0.16,\nand Epeak of 175.8 +- 76.0 keV (chi squared 37.47 for 56 d.o.f.).  For this\nmodel the total fluence in the 15-150 keV band is 1.7 +- 0.0 x 10^-05 erg/cm2\nand the 1-sec peak flux measured from T-177.49 sec in the 15-150 keV band is\n9.0 +- 0.3 ph/cm2/sec.  A fit to a simple power law gives a photon index\nof 1.36 +- 0.04 (chi squared 49.55 for 57 d.o.f.).  All the quoted errors\nare at the 90% confidence level.\n\nThe results of the batgrbproduct analysis are available at\nhttp://gcn.gsfc.nasa.gov/notices_s/634200/BA/",
  "circularId": 17562,
  "createdOn": 1426017522000,
  "email": "james.r.cummings@nasa.gov",
  "subject": "GRB 150309A: Swift-BAT refined analysis",
  "submitter": "Jay R. Cummings at NASA/GSFC/Swift  <james.r.cummings@nasa.gov>",
  "eventId": "GRB 150309A"
}