TITLE:   GCN CIRCULAR
NUMBER:  8259
SUBJECT: Konus-Wind observation of GRB 080916A
DATE:    08/09/17 14:31:01 GMT
FROM:    Valentin Pal'shin at Ioffe Inst  <val@mail.ioffe.ru>

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

The long GRB 080916A (Swift-BAT trigger # 324895:
Ziaeepour et al., GCN 8237, Baumgartner et al. 8243) triggered 
Konus-Wind at T0=35121.715 s UT (09:45:21.715).

The burst light curve shows a single pulse with a duration of ~40 s.

As observed by Konus-Wind the burst
had a fluence of 5.54(-0.66, +0.79)x10^-6 erg/cm2,
and a 256-ms peak flux measured from T0+1.024 s
of 1.05(-0.40, +0.41)x10^-6 erg/cm2/s
(both in the 20 keV - 1 MeV energy range).

The time-integrated spectrum of the burst
(from T0 to T0+33.024 s) is well fitted (in the 20 keV-1 MeV range)
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -1.00(-0.32, +0.38),
and Ep = 129(-21, +33) keV (chi2 = 32.0/51 dof).
Fitting by GRBM (Band) model yields only an upper limit on
the high energy photon index: beta < -2.43.

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

Assuming z = 0.689 (Fynbo et al., GCN 8254) and a standard
cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.27, Omega_\Lambda =
0.73, the isotropic energy release E_iso ~7x10^51 erg, the peak 
luminosity (L_iso)_max ~ 2x10^51 erg/s, and Ep_rest ~220 keV.

The Konus-Wind light curve of this GRB is available
at http://www.ioffe.rssi.ru/LEA/GRBs/GRB080916_T35121/