{
  "bibcode": "2013GCN.15083....1M",
  "body": "C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),\nN. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU),\nA. Melandri (INAF-OAB), D. M. Palmer (LANL), T. Sakamoto (AGU),\nM. Stamatikos (OSU), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team):\n\nUsing the data set from T-60 to T+243 sec from the recent telemetry \ndownlink,\nwe report further analysis of BAT GRB 130807A (trigger #565651)\n(Melandri, et al., GCN Circ. 15082).  The BAT ground-calculated position is\nRA, Dec = 269.801, -27.616 deg, which is\n    RA(J2000)  =  17h 59m 12.4s\n    Dec(J2000) = -27d 36' 56.7\"\nwith an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).\nThe partial coding was 92%.\n\nBased on the currently available event data, the mask-weighted light \ncurve shows an initial FRED-like peak starting at T-10 sec, peaking at \nT=0 sec and decaying to background by T+50 sec.  This is followed by at \nleast two more weaker peaks, one from roughly T+90 sec to T+130 sec and \nthe second beginning at T+160 sec and continuing until the data cuts off \nat T+243 seconds.  The two later peaks are coincident with flares seen \nin the Swift/XRT data.  We note also that the Swift satellite slewed \naway from the source location at ~T+300 seconds, while an XRT flare was \nstill ongoing. Since we do not have all of the data, we cannot determine \nT90 at this time.\n\nThe time-averaged spectrum from T-12.18 to T+163.82 sec is best fit by a \npower law with an exponential cutoff.  This fit gives a photon index \n0.31 +- 0.89,\nand Epeak of 75.9 +- 35.2 keV (chi squared 56.96 for 56 d.o.f.).  For this\nmodel the total fluence in the 15-150 keV band is 1.2 +- 0.2 x 10^-06 \nerg/cm2\nand the 1-sec peak flux measured from T-4.68 sec in the 15-150 keV band is\n0.4 +- 0.1 ph/cm2/sec.  A fit to a simple power law gives a photon index\nof 1.46 +- 0.17 (chi squared 63.40 for 57 d.o.f.).  All the quoted errors\nare at the 90% confidence level.\n\nThe current analysis of the BAT data does not allow us to distinguish \nbetween the interpretations of this event as either a GRB or galactic \ntransient. These results will be updated as more event data becomes \navailable.\n\nExamination of archival images from the Swift/BAT transient monitor \nthrough 3:03 UT, August 6, 2013 (~31.5 hours before the trigger) shows \nno sign of earlier emission from the location of trigger 565651.\n\nThe results of the batgrbproduct analysis are available at\nhttp://gcn.gsfc.nasa.gov/notices_s/565651/BA/",
  "circularId": 15083,
  "createdOn": 1375972514000,
  "email": "hans.krimm@nasa.gov",
  "subject": "GRB 130807A, Swift-BAT refined analysis",
  "submitter": "Hans Krimm at NASA-GSFC  <hans.krimm@nasa.gov>",
  "eventId": "GRB 130807A"
}