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GCN Circular 13917

Subject

GRB 121028A: Swift-BAT refined analysis

Date

2012-10-29T00:53:25Z (11 years ago)

From

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

T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
A. M. Parsons (GSFC), G. Sato (ISAS), M. Stamatikos (OSU),
R. L. C. Starling (U Leicester), J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-61 to T+242 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 121028A (trigger #536897)
(Starling, et al., GCN Circ. 13913Not found
 
 
).  The BAT ground-calculated position is
RA, Dec = 271.903, -2.298 deg, which is 
   RA(J2000)  =  18h 07m 36.7s 
   Dec(J2000) = -02d 17' 52.1" 
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 50%.
 
The mask-weighted light curve shows a single pulse starting at ~T-0.9 sec, 
peaking at ~T+2 sec, and ending ~T+4 sec.  T90 (15-350 keV) is 3.8 +- 0.7 sec
(estimated error including systematics).
 
The time-averaged spectrum from T-0.8 to T+3.8 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.79 +- 0.17.  The fluence in the 15-150 keV band is 3.7 +- 0.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.01 sec in the 15-150 keV band
is 1.9 +- 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/536897/BA/