{
  "bibcode": "2013GCN.14916....1M",
  "body": "C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), T. Sakamoto (AGU),\non behalf of the Swift-BAT team:\n\nUsing the data set from T-25 to T+100 sec from the recent telemetry \ndownlink, we report further analysis of BAT GRB 130612A (trigger \n#557976) (Racusin, et al., GCN Circ. 14874).  The BAT ground-calculated \nposition is\nRA, Dec = 259.771, 16.729 deg which is\n    RA(J2000)  =  17h 19m 05.0s\n    Dec(J2000) = +16d 43' 44.7\"\nwith an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).\nThe partial coding was 34%.\n\nThe mask weighted light curve shows a single FRED-like profile with a \nrise time of about 1 sec near T+0sec and a gradual decay time with \ne-folding time of about 3 sec.  This burst was detected as the Swift \nspacecraft was entering the South Atlantic Anomaly region, and the raw \nbackground counting rate was ramping upward.  The mask weighted light \ncurve does not have a clean background level, so estimating the T90 is \ndifficult.  If we restrict the analysis to the time range T-25 to T+100, \nwe estimate T90 (15-350 keV) to be 4.0 +/- 1.4 sec.  However, we cannot \nrule out the possibility of a faint extended emission tail to \napproximately T+100 (in which case T90 is 110 +/- 60 sec).\n\nThe time-averaged spectrum from T-0.83 to T+3.17 sec is best fit by a \npower law with an exponential cutoff.  This fit gives a photon index \n-0.14 +- 1.71,  and Epeak of 36.4 +- 7.6 keV (chi squared 36 for 56 \nd.o.f.).  For this model the total fluence in the 15-150 keV band is 2.3 \n+- 0.5 x 10^-7 erg/cm2 and the 1-sec peak flux measured from T+0.17 sec \nin the 15-150 keV band is 1.7 +- 0.3 ph/cm2/sec.  A fit to a simple \npower law gives a photon index of 2.06 +- 0.25 (chi squared 44 for 57 \nd.o.f.).  All the quoted errors are at the 90% confidence level.\n\nThe results of the batgrbproduct analysis are available at\nhttp://gcn.gsfc.nasa.gov/notices_s/557976/BA/",
  "circularId": 14916,
  "createdOn": 1371679314000,
  "email": "craigm@milkyway.gsfc.nasa.gov",
  "subject": "GRB 130612A: Swift-BAT refined analysis",
  "submitter": "Craig Markwardt at NASA/GSFC  <craigm@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 130612A"
}