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GCN Circular 11169

Subject
GRB 100901A: Swift-BAT refined analysis
Date
2010-09-02T01:02:07Z (14 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), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
S. Immler (CRESST/GSFC/UMD), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-240 to T+663 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 100901A (trigger #433065)
(Immler, et al., GCN Circ. 11159Loading...
 
 ).  The BAT ground-calculated position is
RA, Dec = 27.252, 22.751 deg, which is 
   RA(J2000)  =  01h 49m 00.5s 
   Dec(J2000) = +22d 45' 02.9" 
with an uncertainty of 3.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 40%.
 
The mask-weighted light curve shows two main peaks.  The first starts at
~T-5 sec, peaks at ~T+5 sec, and ends at ~T+10 sec.  The second starts
at ~T+300 sec, peaks at ~T+390, and ends at ~T+490 sec.  We note that the
burst location went out of the BAT FoV at T+650 sec during a slew
due to an observing constraint.  T90 (15-350 keV) is 439 +- 33 sec
(estimated error including systematics).
 
The time-averaged spectrum from T-2.4 to T+471.8 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.52 +- 0.21.  The fluence in the 15-150 keV band is 2.1 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-1.81 sec in the 15-150 keV band
is 0.8 +- 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/433065/BA/