TITLE:   GCN CIRCULAR
NUMBER:  19913
SUBJECT: Konus-Wind observation of GRB 160910A
DATE:    16/09/12 17:19:40 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova@mail.ioffe.ru>

A. Tsvetkova, S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Lysenko, A. Kozlova and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration, very intense GRB 160910A
(Fermi GBM observation: Veres & Meegan, GCN 19901;
Fermi-LAT detection:  Racusin & Kocevski, GCN 19902;
CALET Gamma-Ray Burst Monitor detection: Kawakubo et al., GCN 19909)
triggered Konus-Wind at T0=62379.089 s UT (17:19:39.089).

The burst light curve starts with an initial weaker emission followed by
a main bright peak with a duration of ~50 s.
The main pulse is followed by a long weak tail seen up to ~T0+150 s.
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst
had a fluence of 1.36(-0.09,+0.10)x10^-4 erg/cm2,
and a 64-ms peak energy flux, measured from T0+5.120 s,
of 3.51(-0.32,+0.32)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(measured from T0 to T0+47.872 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.81(-0.06,+0.07),
the high energy photon index beta = -2.16(-0.12,+0.09),
the peak energy Ep = 315(-29,+31) keV,
chi2 = 97/98 dof.

The spectrum near the peak count rate
(measured from T0+4.864 to T0+6.400 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.15(-0.10,+0.10),
the high energy photon index beta = -2.27(-0.09,+0.07),
the peak energy Ep = 266(-19,+21) keV,
chi2 = 100/69 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB160910_T62379/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.