[vsnet-grb-info 13849] GRB 130831B, Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15163
SUBJECT: GRB 130831B, Swift-BAT refined analysis
DATE:    13/09/01 21:51:29 GMT
FROM:    Tilan Ukwatta at MSU  <tilan.ukwatta at gmail.com>

W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
A. Y. Lien (NASA/GSFC/ORAU), D. Malesani (DARK/NBI),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), G. Sato (ISAS), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+902 sec from the
recent telemetry downlink, we report further analysis
of BAT GRB 130831B (trigger #568855) (Malesani, et al.,
GCN Circ. 15141). The BAT ground-calculated position is
RA, Dec = 192.454, -29.187 deg which is
   RA(J2000)  =  12h 49m 48.9s
   Dec(J2000) = -29d 11' 13.5"
with an uncertainty of 2.1 arcmin, (radius, sys+stat,
90% containment). The partial coding was 14%.

BAT mask-weighted light curve shows a multi peak
episode starting from ~T-12 sec highest peak
around T+1 sec and ending at ~T+30 sec.
T90 (15-350 keV) is 37.8 +- 10.4 sec
(estimated error including systematics).

The time-averaged spectrum from T-13.9 to T+30.6 sec
is best fit by a simple power-law model.  The power
law index of the time-averaged spectrum is 1.88 +- 0.21.
The fluence in the 15-150 keV band is
1.4 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon
flux measured from T-0.05 sec in the 15-150 keV band
is 2.4 +- 0.5 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/568855/BA/