TITLE:   GCN CIRCULAR
NUMBER:  11137
SUBJECT: GRB 100823A: Swift-BAT refined analysis
DATE:    10/08/23 22:25:08 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
V. Mangano (INAF-IASFPA), C. B. Markwardt (GSFC/UMD), T. Sakamoto (GSFC/UMBC),
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+962 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 100823A (trigger #432420)
(Mangano, et al., GCN Circ. 11135).  The BAT ground-calculated position is
RA, Dec = 20.706, 5.848 deg, which is 
   RA(J2000)  =  01h 22m 49.4s 
   Dec(J2000) = +05d 50' 52.6" 
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 92%.
 
The mask-weighted light curve shows a single FRED peak starting at ~T-2 sec,
peaking at ~T+1 sec, and ending at T+150 sec.  T90 (15-350 keV) is
16.9 +- 3.5 sec (estimated error including systematics).
 
The time-averaged spectrum from T-1.2 to T+18.2 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.19 +- 0.18.  The fluence in the 15-150 keV band is 4.1 +- 0.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.14 sec in the 15-150 keV band
is 1.0 +- 0.1 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/432420/BA/