[vsnet-grb-info 8325] Konus-Wind observations of GRB 090827

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9848
SUBJECT: Konus-Wind observations of GRB 090827
DATE:    09/08/30 15:23:12 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred at 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 090827 (Cummings et al., GCN 9846)
triggered Konus-Wind at T0=68787.702 s UT (19:06:27.702)

The burst time profile had a FRED-like structure with a duration of ~8 s.
The Konus-Wind light curves of this GRB are available at
http://www.ioffe.ru/LEA/GRBs/GRB090827_T68787/

As observed by Konus-Wind the burst had
a fluence of 3.0(-0.5,+0.6)x10-6 erg/cm2, and
a 256-ms peak flux, measured from T0-0.256,
of 1.7(-0.5,+0.7)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+8.848 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 = -0.6(-0.45,+0.58),
and  Ep = 200(-39,+69)keV (chi2 = 62/57 dof).

Fitting by the GRB (Band) model yields the same alpha and Ep
values with the high energy photon index Beta of -9 (< -2.3)

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