GCN Circular 17774
Subject
GRB 150428A: Swift-BAT refined analysis
Date
2015-04-28T12:49:41Z (10 years ago)
From
Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>
W. H. Baumgartner (GSFC/UMBC), 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), K. L. Page (U Leicester), 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 the recent telemetry downlink,
we report further analysis of BAT GRB 150428A (trigger #639275)
(Page, et al., GCN Circ. 17765). The BAT ground-calculated position is
RA, Dec = 188.539, 6.967 deg which is
RA(J2000) = 12h 34m 09.3s
Dec(J2000) = +06d 58' 00.8���
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 16%.
The mask-weighted light curve shows a multi-peaked structure that starts at
~ T-40 sec and ends at ~ T+60 sec. T90 (15-350 keV) is 53.2 +- 15.1 sec
(estimated error including systematics).
The time-averaged spectrum from T-39.0 to T+38.6 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is 1.28 +- 0.09.
The fluence in the 15-150 keV band is 6.3 +- 0.3 x 10^-6 erg/cm2. The 1-sec peak
photon flux measured from T+17.4 sec in the 15-150 keV band is 3.0 +- 0.5 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/639275/BA/