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GCN Circular 18368

Subject

GRB 150925A: Swift-BAT refined analysis

Date

2015-09-25T16:46:23Z (9 years ago)

From

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

T. Sakamoto (AGU), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), J. L. Racusin (NASA/GSFC),
M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+963 sec from the recent telemetry downlinks,
we report further analysis of BAT GRB 150925A (trigger #656604)
(Racusin, et al., GCN Circ. 18365Not found
 
 
).  The BAT ground-calculated position is
RA, Dec = 227.538, -19.640 deg, which is 
   RA(J2000)  =  15h 10m 09.0s 
   Dec(J2000) = -19d 38' 22.3" 
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 56%.
 
The mask-weighted light curve show several overlapping peaks starting at ~T-0,
peaking at ~T+25 sec, and ending at ~T+180 sec.  T90 (15-350 keV) is
121 +- 27 sec (estimated error including systematics).
 
The time-averaged spectrum from T+3.51 to T+149.61 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.19 +- 0.20.  The fluence in the 15-150 keV band is 1.4 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+30.68 sec in the 15-150 keV band
is 0.6 +- 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/656604/BA/