TITLE:   GCN CIRCULAR
NUMBER:  10209
SUBJECT: Konus-Wind observation of GRB 091127
DATE:    09/11/30 12:11:49 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 GRB 091127 (Swift-BAT trigger #377179:
Troja et al., GCN 10191; Stamatikos et al., 10197)
triggered Konus-Wind at T0=84349.449 s UT (23:25:49.449).

The burst light curve consists of two main peaks, and a third, softer
peak. A total duration of the burst ~10 s. The Konus-Wind light
curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB091127_T84349/

As observed by Konus-Wind the burst
had a fluence of 1.22(+/-0.06)x10-5 erg/cm2,
and a 64-ms peak flux measured from T0 + 0.256s
of 8.3(+/-0.1)x10-6 erg/cm2/s
(both in the 20 keV - 2 MeV energy range).

The time-integrated spectrum of the burst
(from T0 to T0+8.448 s) is well fitted
in the 20 keV - 2 MeV range by a power law
with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep), with
alpha = -1.95(-0.1, +0.1),
and Ep = 21.3(-3, +4) keV (chi2 = 57/58 dof).

The spectrum of the most intense peak (measured
from T0 to T0+0.256 s) is also well fitted
in the 20 keV - 2 MeV range by a power law
with exponential cutoff model, for which
alpha = -1.6(-0.2, +0.2),
and Ep = 130(-32, +41) keV (chi2 = 16/27 dof).

Assuming z = 0.49 (Cucchiara et al., GCN 10202) 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 ~7.7x10^51 erg,
the peak luminosity (L_iso)_max ~7.8x10^51 erg/s.

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