[vsnet-grb-info 16732] GRB 150710B refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18013
SUBJECT: GRB 150710B refined analysis
DATE:    15/07/11 23:18:10 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <james.r.cummings at nasa.gov>

J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
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-47 to T+50 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150710B.  (Cummings, et al., GCN Circ.
18009).  The refined BAT position is RA, Dec = 83.191, -46.960 deg, which is
    RA(J2000)  =  05h 32m 45.8s
    Dec(J2000) = -46d 57' 34"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
  
The mask-weighted light curve shows 6 overlapping but well-defined peaks
followed by an exponential decay to background.  T90 (15-350 keV) is
15 +- 1 sec (estimated error including systematics).
  
The time-averaged spectrum from T+0 to T+15 sec is best fit by a model of a
power law with an exponential cutoff.  The photon index of the time-averaged
spectrum is 0.99 +- 0.09.  Epeak was 166 +- 28 keV.  Using this model, the
fluence in the 15-150 keV band was (3.5 +- 0.1) x 10^-6 ergs/cm^2.  A simple
power-law fit has a photon index of 1.34 +- 0.02.

The 1-sec peak photon flux measured from T+3.5 sec in the 15-150 keV band
was 8.3 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

A Swift TOO is being executed (Evans, GCN #18010).

Because this was a ground-detected burst, the usual automated BAT data
products are not available.