TITLE:   GCN CIRCULAR
NUMBER:  18622
SUBJECT: GRB 151118A, Swift-BAT refined analysis
DATE:    15/11/20 00:36:34 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

C. B. Markwardt (GSFC), A. Amaral-Rogers (U Leicester), S. D. Barthelmy (GSFC),
J. R. Cummings (GSFC/UMBC), 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+941 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 151118A (trigger #664078)
(Amaral-Rogers, et al., GCN Circ. 18611).  The BAT ground-calculated position is
RA, Dec = 57.169, 65.889 deg which is
  RA(J2000)  =  03h 48m 40.6s
  Dec(J2000) = +65d 53' 22.0"
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 98%.

The mask-weighted light curve shows a multi-peaked structure that
starts at ~ T0 and ends at ~T+30 s. The structure contains roughly two main
pulses that peak at ~ T0 and ~T+7 s, respectively. T90 (15-350 keV) is
23.4 +- 10.5 sec (estimated error including systematics).

The time-averaged spectrum from T+0.0 to T+30.8 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.80 +- 0.20.  The fluence in the 15-150 keV band is 4.5 +- 0.6 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+6.41 sec in the 15-150 keV band
is 1.2 +- 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/664078/BA/