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GCN Circular 8468

Subject

GRB 081102: Swift-BAT refined analysis

Date

2008-11-03T13:22:28Z (16 years ago)

From

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

E. E. Fenimore (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
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-240 to T+962 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 081102 (trigger #333427)
(Ukwatta, et al., GCN Circ. 8462Loading...
 
 ).  The BAT ground-calculated position is
RA, Dec = 331.178, 52.991 deg, which is 
   RA(J2000)  =  22h 04m 42.6s 
   Dec(J2000) = +52d 59' 27.7" 
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 36%.
 
The mask-weighted light curve shows two overlapping peaks, the first starting
at ~T-20 sec, peaking at ~T-15 sec, and hitting a minimum between the two
peaks at ~T-7 sec.  The second peak peaks at ~T+1 sec, and returns to background
at ~T+90 sec.  T90 (15-350 keV) is 63 +- 16 sec (estimated error
including systematics).
 
The time-averaged spectrum from T-20.2 to T+62.8 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.73 +- 0.13.  The fluence in the 15-150 keV band is 2.3 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.08 sec in the 15-150 keV band
is 1.4 +- 0.3 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/333427/BA/