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GCN Circular 8647

Subject
Konus-Wind observation of GRB 081209
Date
2008-12-10T17:49:19Z (15 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 short hard GRB 081209 (Golenetskii et al., GCN 8646; Fermi GBM 
trigger 250558317) triggered Konus-Wind at T0=84720.033 s UT (23:32:00.033).

As observed by Konus-Wind the burst
had a fluence of 2.39(-0.52, +0.58)x10^-6 erg/cm2,
and a 16-ms peak flux measured from T0-0.012 s
of 2.68(-0.83, +0.87)x10^-5 erg/cm2/s
(both in the 20 keV - 3 MeV energy range).

The spectrum accumulated from T0 to T0+0.128 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 = -0.33(-0.31, +0.41),
and Ep = 961(-257, +432) keV (chi2 = 11.2/17 dof).
Fitting by GRB (Band) model yields the same alpha and Ep,
and only an upper limit on the high energy
photon index: beta < -1.7 (chi2 = 11.2/16 dof).

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