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GCN Circular 13772

Subject

GRB 120913B: Swift-BAT refined analysis

Date

2012-09-15T02:15:18Z (12 years ago)

From

Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), E. A. Helder (PSU),
H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
 
Using the data set from T-240 to T+882 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 120913B (trigger #533613)
(Helder, et al., GCN Circ. 13763Loading...
 
 ).  The BAT ground-calculated position is
RA, Dec = 213.660, -14.508 deg, which is 
   RA(J2000)  =  14h 14m 38.3s 
   Dec(J2000) = -14d 30' 27.9" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 59%.
 
The mask-weighted light curve shows two main pulses riding on top of a broad peak.
The burst starts at ~T-50 sec, with peaks at ~T+5 and ~T+39 sec, and ending at ~T+140 sec.
T90 (15-350 keV) is 126 +- 4 sec (estimated error including systematics).
 
The time-averaged spectrum from T-51.70 to T+111.79 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.63 +- 0.04.  The fluence in the 15-150 keV band is 1.11 +- 0.02 x 10^-5 erg/cm2.
The 1-sec peak photon flux measured from T+38.46 sec in the 15-150 keV band
is 3.2 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/533613/BA/