{
  "bibcode": "2011GCN.12144....1C",
  "body": "J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC),\nW. H. Baumgartner (GSFC/UMBC),  E. E. Fenimore (LANL), N. Gehrels (GSFC),\nH. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL),\nA. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC),\nM. Stamatikos (OSU/NASA/GSFC), J. Tueller (GSFC), T. N. Ukwatta (GWU)\n(i.e. the Swift-BAT team):\n\nUsing the data set from T-240 to T+1608 sec, we report further analysis\nof BAT GRB 110709B (triggers #456967 and #456969) (Cummings, et al.,\nGCN Circ. 12122, Barthelmy, et al., GCN Circ. 12124, and Barthelmy, et\nal., GCN Circ. 12130), where T is the time of the first trigger.\n\nThe BAT ground-calculated position for the second event (trigger #456969)\nis RA, Dec = 164.655, -23.456 deg which is\n      RA(J2000)  =  10h 58m 37.3s\n      Dec(J2000) = -23d 27' 20.9\"\nwith an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).\nThe partial coding was 100%.  This position is 1.0 arcmin from the ground-\ncalculated position of the first event (trigger #456967), which had an\nestimated uncertainty of 1.1 arcmin.  The position of 456969 is\n0.07 arcmin from the enhanced XRT position (Beardmore et al., GCN Circ\n12136).  The two events are clearly from the same object.\n\nThe main emission in the first event lasted from about T-28 sec to\nT+55 sec with a faint declining emission detectable to about T+180 sec.\nT90 (15-350 keV) of the first event was 55.6 +- 3.2 sec.  There was no\nflux detectable in BAT from about T+180 to about T+485 sec.  The second\nevent lasted from T+485 sec to T+865 sec with a variety of peaks and\nspikes on top of an ongoing emission.  T90 (15-350 keV) of the second\nevent was 259.2 +- 8.8 sec (estimated error including systematics).\nConsidering the two events as a whole, T90 was about 846 +- 6 seconds.\nThe lightcurve of the second event was clearly different from the first,\nso the unusual separation of two episodes of bright emission was not the\nresult of gravitational lensing.\n\nThe separation of episodes is unusual but not unprecedented. For instance,\nGRBs 041219A, 060124, 070721B, and 050820A also had multiple episodes\nseparated by long intervals with no detectable emission.\n\nThe source came into the BAT FOV at ~T-75 (during a slew that started at\nT-200sec and settled at ~T-20 sec.).  The source was above the Earth\nhorizon for about 20 minutes prior to trigger 456967.  We cannot rule out\nfaint or soft emission prior to about T-75 sec, but for 20 minutes prior\nto the first trigger, there was no strong emission above about 50 keV.\n\nThe time-averaged spectrum of the data for the first trigger, trigger\n#456967, from T-27.4 to T+46.7 sec is best fit by a simple power-law model.\nThe power law index of the time-averaged spectrum is 1.29 +- 0.04.  The\nfluence in the 15-150 keV band is 9.4 +- 0.2 x 10-6 erg/cm2.  The 1-sec\npeak photon flux measured from T+13.59 sec in the 15-150 keV band is\n3.4 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence\nlevel.\n\nThe time-averaged spectrum from T+518.5 to T+855.3 sec is best fit by a\nsimple power-law model.  The power law index of the time-averaged spectrum\nis 1.44 +- 0.04.  The fluence in the 15-150 keV band is\n1.44 +- 0.04 x 10^-05 erg/cm2.  The 1-sec peak photon flux measured from\nT+1.06 sec in the 15-150 keV band is 3.9 +- 0.2 ph/cm2/sec.  All the quoted\nerrors are at the 90% confidence level.\n\nExamination of archival pre-trigger data from when the location of\nGRB 110709B was in the BAT field of view reveals no significant precursor\nemission.  In the two observations closest in time to the trigger,  upper\nlimits are set at 0.005 ct/s/cm2 (T-6903 to T-6345 sec) and 0.004 ct/s/cm2\n(T-12526 to T-11986 sec) and T-6903 to T-6345 sec).  There is also no\nemission detected in daily averages going back to 2011 June 1, with an\naverage upper limit of 0.002 ct/s/cm2 (~8 mCrab).  All errors are 1-sigma\nfor the 15-50 keV energy band.\n\nIn the 70-month averaged BAT Hard X-ray Survey, the three-sigma upper limit\nat the position of the XRT counterpart for GRB 110709B is\n6.4e-12 ergs/cm2/sec in the 14-195 keV band.\n\nThe results of the batgrbproduct analysis are available at\n     Trigger 456967:  http://gcn.gsfc.nasa.gov/notices_s/456967/BA/\n     Trigger 456969:  http://gcn.gsfc.nasa.gov/notices_s/456969/BA/\n   http://gcn.gsfc.nasa.gov/notices_s/comb_456967_456969/BA/top.html",
  "circularId": 12144,
  "createdOn": 1310338809000,
  "email": "james.r.cummings@nasa.gov",
  "subject": "GRB 110709B BAT refined analysis",
  "submitter": "Jay R. Cummings at NASA/GSFC/Swift  <james.r.cummings@nasa.gov>",
  "eventId": "GRB 110709B"
}