[vsnet-grb-info 18286] GRB 160726A, Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19734
SUBJECT: GRB 160726A, Swift-BAT refined analysis
DATE:    16/07/27 01:18:02 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien at nasa.gov>

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),
J. P. Norris (BSU), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
R. L. C. Starling (U Leicester), 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 160726A (trigger #706052)
(Starling et al., GCN Circ. 19731).  The BAT ground-calculated position is
RA, Dec = 98.809, -6.617 deg which is
  RA(J2000)  =  06h 35m 14.2s
  Dec(J2000) = -06d 37' 03.0"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 58%.

The mask-weighted light curve shows a double-peaked structure that
starts at ~T0 and ends at ~T+0.8 s, with the two peaks at ~ T0 and ~T+0.6 s,
respectively. T90 (15-350 keV) is 0.7 +- 0.04 sec (estimated error including
systematics).

The time-averaged spectrum from T+0.0 to T+0.8 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.26 +- 0.13.  The fluence in the 15-150 keV band is 2.6 +- 0.2 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.11 sec in the 15-150 keV band
is 3.2 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

Using a 4-ms binned light curve, the lag analysis finds a lag of
is -3.5 +/- 3 ms for the 100-350 keV to 25-50 keV, and -5 +/- 6 ms for
the 50-100 keV to 15-25 keV band. These numbers are consistent with
those of a short GRB.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/706052/BA/