TITLE:   GCN CIRCULAR
NUMBER:  19900
SUBJECT: Konus-Wind observation of GRB 160905A
DATE:    16/09/06 16:15:22 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, hard-spectrum GRB 160905A (Swift-BAT trigger #711084:
D'Avanzo et al., GCN 19887; Barthelmy et al., GCN 19896;
Fermi GBM observation: Bissaldi, GCN 19889;
Fermi-LAT detection: McEnery et al., GCN 19890)
triggered Konus-Wind at T0=40735.196 s UT (11:18:55.196).

The burst light curve shows a double-peaked structure with a total 
duration of ~44 s.
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst
had a fluence of 1.50(-0.11,+0.11)x10^-4 erg/cm2,
and a 64-ms peak energy flux, measured from T0+10.224 s,
of 1.17(-0.23,+0.23)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+42.240 s)
is best fit in the 20 keV - 18 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.70(-0.05,+0.06),
the high energy photon index beta = -2.39(-0.26,+0.16),
the peak energy Ep = 594(-50,+56) keV,
chi2 = 124/97 dof.

The spectrum near the peak count rate
(measured from T0+7.424 to T0+12.288 s)
is best fit in the 20 keV - 18 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.65(-0.08,+0.09),
the high energy photon index beta = -2.53(-0.44,+0.25),
the peak energy Ep = 664(-81,+88) keV,
chi2 = 96/83 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB160905_T40735/

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