TITLE:   GCN CIRCULAR
NUMBER:  8557
SUBJECT: GRB 081126: Swift-BAT refined analysis
DATE:    08/11/27 02:23:00 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

G. Sato (ISAS), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), R. Margutti (U Bicocca&OAB), C. B. Markwardt (GSFC/UMD),
D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (GSFC/ORAU),
J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-120 to T+183 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 081126 (trigger #335647)
(Margutti, et al., GCN Circ. 8554).  The BAT ground-calculated position is
RA, Dec = 323.526, 48.714 deg, which is 
   RA(J2000)  =  21h 34m 06.3s 
   Dec(J2000) = +48d 42' 51.0" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 67%.
 
The mask-weighted light curve shows a small peak starting at ~T-30 sec,
peaking at ~T-18 sec, and returning almost to zero at T-7 sec, at which time
the second peak starts to rise.  It peaks at ~T+1.5 sec and reachs a maximum
at ~T+7 sec.  The third peak peaks at ~T+31.5 sec and ends at ~T+100 sec.
T90 (15-350 keV) is 54 +- 4 sec (estimated error including systematics).
 
The time-averaged spectrum from T-21.4 to T+45.9 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.27 +- 0.06.  The fluence in the 15-150 keV band is 3.3 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.75 sec in the 15-150 keV band
is 3.7 +- 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/335647/BA/