GCN Circular 12270

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 short-duration extremely hard GRB 110808A
(localized by IPN: Hurley et al., GCN 12269
Not found
 
 
)
triggered Konus-Wind at T0=56695.237s UT (15:44:55.237)

The burst light curve shows a single bright hard pulse,
with a duration of ~0.5 s and much weaker tail of
the emission which is detectable till T0+8 s.
The emission is seen up to 13 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB110808_T56695/

As observed by Konus-Wind the burst
had a fluence of (1.6 � 0.2)x10-5 erg/cm2,
and a 16-ms peak flux, measured from T0+0.112 s,
of (1.1 � 0.2)x10-4 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The spectrum of the burst (measured from T0 to T0+0.256 s)
is best fitted in the 20 keV - 10 MeV range
by a power law with exponential cutoff model, for which
alpha = -1.13 (-0.08, +0.08),
and Ep = 2960(-796, +1217) keV,
chi2 = 53.2/45 dof.
Fitting this spectrum by the GRB (Band) function yields
the following model parameters:
the low-energy photon index alpha = -1.13 (-0.08, +0.07),
the high energy photon index beta = -2.5 (<-1.9),
the peak energy Ep = 2630(-744, +836) keV,
chi2 = 54.3/44 dof.

The spectrum at the maximum count rate
(measured from T0+0.064 to T0+0.128 s)
is best fitted in the 20 keV - 10 MeV range
by a power law with exponential cutoff model, for which
alpha = -1.07 (-0.11, +0.12),
and Ep = 4238(-1530, +3270) keV,
chi2 = 12.5/16 dof.

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