[vsnet-grb-info 6632] GRB 080915B, Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8236
SUBJECT: GRB 080915B, Swift-BAT refined analysis
DATE:    08/09/15 19:49:30 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

K. McLean (GSFC/UMD), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL),
A. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS),
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU),
H. Ziaeepour (UCL-MSSL)
(i.e. the Swift-BAT team):
 
Using the data set from T-28 to T+930 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 080915B (trigger #324805)
(Ziaeepour, et al., GCN Circ. 8234).  The BAT ground-calculated position is
RA, Dec = 213.088, -11.491 deg, which is 
   RA(J2000)  =  14h 12m 21.2s 
   Dec(J2000) = -11d 29' 26.9" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 74%.
 
The mask-weighted light curve shows a roughly symmetric peak starting
at ~T-0.5 sec, peaking at ~T+0.6 sec, and ending at ~T+4.5 sec.
T90 (15-350 keV) is 3.9 +- 0.7 sec (estimated error including systematics).
 
The time-averaged spectrum from T-0.5 to T+6.1 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 1.48 +- 0.35, 
and Epeak of 42.3 +- 9.1 keV (chi squared 54.5 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 9.9 +- 0.6 x 10^-7 erg/cm2
and the 1-sec peak flux measured from T+0.18 sec in the 15-150 keV band is
8.5 +- 0.3 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 2.02 +- 0.08 (chi squared 62.6 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/324805/BA/