[vsnet-grb-info 16774] GRB 150724A: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18055
SUBJECT: GRB 150724A: Swift-BAT refined analysis
DATE:    15/07/24 12:10:27 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

D. M. Palmer (LANL), 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), J. L. Racusin (NASA/GSFC), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
 
Using the data set from T-240 to T+902 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 150724A (trigger #650141)
(Racusin, et al., GCN Circ. 18050).  The BAT ground-calculated position is
RA, Dec = 97.549, -19.147 deg, which is 
   RA(J2000)  =  06h 30m 11.7s 
   Dec(J2000) = -19d 08' 48.1" 
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 48%.
 
The mask-weighted light curve has at least 4 peaks starting at ~T-10 sec,
with peaks at ~T+1 sec, ~T+24 sec, ~T+160 sec, & ~T+220 sec, and the
emission ending at ~T+300 sec.  T90 (15-350 keV) is 280 +- 44 sec
(estimated error including systematics).
 
The time-averaged spectrum from T-1.07 to T+325.42 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.06 +- 0.15.  The fluence in the 15-150 keV band is 2.2 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+24.08 sec in the 15-150 keV band
is 0.9 +- 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/650141/BA/