[vsnet-grb-info 10779] GRB 110726A: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  12201
SUBJECT: GRB 110726A: Swift-BAT refined analysis
DATE:    11/07/26 11:38:19 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

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
http://gcn.gsfc.nasa.gov/notices_s/458059/BA/