TITLE:   GCN CIRCULAR
NUMBER:  18469
SUBJECT: GRB 151023A: Swift-BAT refined analysis
DATE:    15/10/24 19:18:03 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),  J. R. Cummings (GSFC/UMBC),
P. D'Avanzo (INAF-OAB), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
A. Y. Lien (GSFC/UMBC), 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 151023A (trigger #661253)
(D'Avanzo, et al., GCN Circ. 18450).  The BAT ground-calculated position is
RA, Dec = 271.012, -8.289 deg which is
  RA(J2000)  =  18h 04m 02.9s
  Dec(J2000) = -08d 17' 19.7"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 83%.

The mask-weighted light curve shows a single-pulse structure that starts at ~ T-1 s,
peaks at ~T0, and ends at ~ T+10 s. T90 (15-350 keV) is 10.66 +- 4.41 sec
(estimated error including systematics).

The time-averaged spectrum from T-0.65 to T+12.16 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.24 +- 0.24.  The fluence in the 15-150 keV band is 2.6 +- 0.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.03 sec in the 15-150 keV band
is 1.1 +- 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/661253/BA/