[vsnet-grb-info 2143] GRB 050915: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3982
SUBJECT: GRB 050915: Swift-BAT refined analysis
DATE:    05/09/15 15:53:42 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <jayc at milkyway.gsfc.nasa.gov>

S. Barthelmy (GSFC), L. Barbier (GSFC), J. Cummings (GSFC/NRC),
E. Fenimore (LANL), N. Gehrels (GSFC), D. Hinshaw (GSFC-SPSYS),
D. Hullinger (UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD),
P. Meszaros (PSU), D. Palmer (LANL), A. Parsons (GSFC),
T. Sakamoto (GSFC/NRC), G. Sato (ISAS), J. Tueller (GSFC),
on behalf of the Swift-BAT team:

Using the data set from T-100 to T+300 sec from the recent telemetry
downlink, we report further analysis of Swift-BAT GRB 050915 (trigger
#155242)  (Grupe, et al., GCN 3977).  The refined BAT ground position is
RA,Dec = 81.682d,-28.010d {5h26m43.7s,-28d0'36"} [J2000] +/- 1.4 arcmin,
(radius, sys+stat, 90% containment).  This position is 25 arcsec from 
the XRT afterglow position reported in Kennea, et al. (GCN circ. 3979).  
The partial coding was 75%.

The light curve shows about seven 2-second long peaks from T-10 to 
T+20 sec and one more peak at about T+43 sec.  T90 (15-350 keV) is 
53 +- 3 sec (estimated error including systematics).

The time-averaged spectrum from T-8 to T+56 sec is well fit by a
simple power law.  The power law index is 1.36 +- 0.16.  The fluence
in the 15-150 keV band is 8.8 +- 0.9 x 10^-7 erg/cm2.  The 1-sec peak
photon flux measured from T+13.7 sec in the 15-150 keV band is
0.8 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.