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GCN Circular 8776

Subject
Konus-Wind observation of GRB 090102
Date
2009-01-03T12:32:25Z (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 long GRB 090102 (Swift-BAT trigger #338895: Mangano et al., GCN 
8762; Sakamoto et al., GCN 8769) triggered Konus-Wind at T0=10536.283 s 
UT (02:55:36.283).

The burst light curve shows a multipeaked structure with a duration of 
~30 s.

As observed by Konus-Wind the burst
had a fluence of 3.09(-0.25, +0.29)x10^-5 erg/cm2,
and a 256-ms peak flux measured from T0+12.016 s
of 5.10(-0.72, +0.74)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+33.024 s) can be 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 = -0.86(-0.13, +0.14),
and Ep = 451(-58, 73) keV (chi2 = 48.8/65 dof).
Fitting by GRB (Band) model yields the same alpha and Ep,
and only an upper limit on the high energy
photon index: beta < -2.73 (chi2 = 68.8/64 dof).

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

Assuming z = 1.547 (de Ugarte Postigo et al., GCN 8766)
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 ~1.9x10^53 erg,
the peak luminosity (L_iso)_max ~ 7.8x10^52 erg/s, and Ep_rest ~1100keV.

The Konus-Wind light curve of this GRB is available
at http://www.ioffe.ru/LEA/GRBs/GRB090102_T10536/
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