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GCN Circular 18148

Subject

GRB 150817A: Swift-BAT refined analysis

Date

2015-08-17T14:18:27Z (9 years ago)

From

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

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
V. D'Elia (ASDC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), T. Sakamoto (AGU),
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 recent telemetry downlinks,
we report further analysis of BAT GRB 150817A (trigger #652334)
(D'Elia, et al., GCN Circ. 18143Not found
 
 
).  The BAT ground-calculated position is
RA, Dec = 249.635, -12.050 deg, which is 
   RA(J2000)  =  16h 38m 32.3s 
   Dec(J2000) = -12d 03' 01.7" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 71%.
 
The mask-weighted light curve shows multiple strong peaks starting at ~T-20,
with the brightest peak at ~T+12 sec and ending at ~T+70 sec.
T90 (15-350 keV) is 38.8 +- 2.1 sec (estimated error including systematics).
 
The time-averaged spectrum from T-16.76 to T+53.28 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.78 +- 0.04.  The fluence in the 15-150 keV band is 5.9 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+11.22 sec in the 15-150 keV band
is 9.6 +- 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/652334/BA/