[vsnet-grb-info 17191] GRB 151031A: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18542
SUBJECT: GRB 151031A: Swift-BAT refined analysis
DATE:    15/10/31 14:25:39 GMT
FROM:    Hans Krimm at NASA-GSFC  <hans.a.krimm at nasa.gov>

T. N. Ukwatta (LANL),S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU),
E. Sonbas (Adiyaman Univ.), M. Stamatikos (OSU), (i.e. the Swift-BAT team):

Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 151031A (trigger #662330)
(Sonbas, et al., GCN Circ. 18538).  The BAT ground-calculated position is
RA, Dec = 83.189, -39.125 deg which is
    RA(J2000)  =  05h 32m 45.3s
    Dec(J2000) = -39d 07' 28.3"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 67%.

The mask-weighted light curve shows a single FRED-shaped peak, peaking at T+2 sec
and returning to background by T+7 sec. T90 (15-350 keV) is 5.00 +- 2.24 sec
(estimated error including systematics).

The time-averaged spectrum from T+0.30 to T+6.30 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.41 +- 0.18.  The fluence in the 15-150 keV band is 3.2 +- 0.3 x 10^-7erg/cm2.
The 1-sec peak photon flux measured from T+1.30 sec in the 15-150 keV band
is 1.7 +- 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/662330/BA/