TITLE:   GCN CIRCULAR
NUMBER:  13781
SUBJECT: Konus-Wind observation of GRB 120916A
DATE:    12/09/18 15:28:42 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf
of the Konus-Wind team, report:

The long-duration GRB 120916A
(Fermi-LAT detection: Vianello et al., GCN 13777;
IPN detection and localization: Hurley et al., GCN 13778)
triggered Konus-Wind at T0=14864.136s UT (04:07:44.136)

The light curve shows a multi-peaked structure with
a total duration of ~30 s followed by a weaker and softer pulse at ~T0+50 s.
The emission in the main bursting episode is seen up to 9 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB120916_T14864/

As observed by Konus-Wind, the burst
had a fluence of 1.7(-0.3,+0.3)x10-5 erg/cm2,
and a 64-ms peak flux, measured from T0+4.864 s,
of 4.5(-1.5,+1.5)x10-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+24.832 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -1.0 (-0.1, +0.2),
the high energy photon index beta = -4.2 (-5.8, +1.6),
the peak energy Ep = 335(-90, +65) keV,
chi2 = 71.5/90 dof.

The spectrum at the maximum count rate (measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.7 (-0.2, +0.2),
the high energy photon index beta = -2.3 (-7.7, +0.2),
the peak energy Ep = 320(-70, +120) keV,
chi2 = 97.9/86 dof.


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