{
  "subject": "GRB 130609B, Swift-BAT refined analysis",
  "eventId": "GRB 130609B",
  "bibcode": "2013GCN.14862....1L",
  "createdOn": 1370900345000,
  "circularId": 14862,
  "submitter": "Hans Krimm at NASA-GSFC  <hans.krimm@nasa.gov>",
  "email": "hans.krimm@nasa.gov",
  "body": "A. Y. Lien (NASA/GSFC/ORAU), S. D. Barthelmy (GSFC),\nW. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),\nN. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC),\nD. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU),\nJ. Tueller (GSFC), T. N. Ukwatta (MSU)\n(i.e. the Swift-BAT team):\n\nUsing the data set from T-60 to T+243 sec from the recent telemetry downlink,\nwe report further analysis of BAT GRB 130609B (trigger #557828)\n(Krimm, et al., GCN Circ. 13841).  The BAT ground-calculated position is\nRA, Dec = 53.776, -40.168 deg which is\n     RA(J2000)  =  03h 35m 06.2s\n     Dec(J2000) = -40d 10' 04.0\"\nwith an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).\nThe partial coding was 43%.\n\nThe mask-weighted light curve shows an initial complex of two main\noverlapping peaks with numerous subsidiary peaks, with strong emission\nbetween T-10 and T+50 sec and low-level emission between T-30 and T+120 sec.\nThe highest points are at T+4 and T+18 sec.  Then there is a second, weaker\nand softer pair of overlapping peaks between T+160 sec and T+220 sec.  This\nsecond set of peaks is consistent with a flare seen in the Swift-XRT.\nT90 (15-350 keV) is 191.98 +- 2.44 sec (estimated error including systematics)\nWe note that receipt of the full event data for GRB 130609B may reveal\nfurther late-time peaks and require a revision of the T90 estimate.  We will\nreport on the full data set in a later Circular.\n\nThe time-averaged spectrum from T-7.84 to T+213.25 sec is best fit by a simple\npower-law model.  The power law index of the time-averaged spectrum is\n1.23 +- 0.04.  The fluence in the 15-150 keV band is 1.6 +- 0.0 x 10^-05\nerg/cm2. The 1-sec peak photon flux measured from T+16.78 sec in the 15-150 keV\nband is 8.5 +- 0.4 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/557828/BA/"
}