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GCN Circular 12201

GRB 110726A: Swift-BAT refined analysis
2011-07-26T11:38:19Z (13 years ago)
Scott Barthelmy at NASA/GSFC <>
J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (MSU), C. A. Wolf (PSU)
(i.e. the Swift-BAT team):
Using the data set from T-240 to T+572 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 110726A (trigger #458059)
(Wolf, et al., GCN Circ. 12196).  The BAT ground-calculated position is
RA, Dec = 286.713, 56.070 deg which is 
   RA(J2000)  =  19h 06m 51.2s 
   Dec(J2000) = +56d 04' 11.0" 
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
The mask-weighted light curve shows a single peak starting at ~T-1 sec,
peaking at ~T+2 sec, and ending at ~T+5 sec.  T90 (15-350 keV) is
5.2 +- 1.1 sec (estimated error including systematics).
The time-averaged spectrum from T-0.9 to T+5.0 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.64 +- 0.87, 
and Epeak of 46.5 +- 11.8 keV (chi squared 79.8 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 2.2 +- 0.3 x 10^-7 erg/cm2
and the 1-sec peak flux measured from T+0.61 sec in the 15-150 keV band is
1.0 +- 0.2 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.86 +- 0.18 (chi squared 87.7 for 57 d.o.f.).  All the quoted errors
are at the 90% confidence level. 
The results of the batgrbproduct analysis are available at
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