GCN Circular 9976
Subject
Konus-Wind observation of GRB 090929A
Event
Date
2009-09-30T16:16:53Z (17 years ago)
From
Valentin Pal'shin at Ioffe Inst <val@mail.ioffe.ru>
S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the
Konus-Wind team, report:
The bright GRB 090929A (Fermi-GBM trigger trigger 275891585:
Rau, GCN 9962) localized by Swift-BAT (Cummings and Krimm, GCN 9966)
triggered Konus-Wind at T0=16387.790 s UT (04:33:07.790).
As observed by Konus-Wind the burst
had a fluence of 1.32(-0.24, +0.23)x10^-5 erg/cm2,
and a 16-ms peak flux measured from T0+0.736 s
of 2.04(-0.61, +0.60)x10^-5 erg/cm2/s
(both in the 20 keV - 3 MeV energy range).
The time-integrated spectrum of the burst (from T0 to T0+8.448 s)
is well fitted (in the 20 keV - 3 MeV range)
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep), with
alpha = -0.47(-0.22, +0.25), and
Ep = 574(-100, +151) keV (chi2 = 66.2/65 dof).
Fitting by GRB (Band) model yields:
the low-energy photon index alpha = -0.36(-0.29, +0.62),
the high energy photon index beta = -2.16(-1.41, +0.43),
the peak energy Ep = 494(-191, +175) keV (chi2 = 62.1/64 dof).
These values are consistent with the Konus-RF results (Golenetskii et
al., GCN 9968).
All the quoted errors are at the 90% confidence level.
The Konus-Wind light curve of this GRB is available
at http://www.ioffe.ru/LEA/GRBs/GRB090929_T16384/