[vsnet-grb-info 7140] Konus-Wind observation of GRB 081222

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8721
SUBJECT: Konus-Wind observation of GRB 081222
DATE:    08/12/24 14:14:00 GMT
FROM:    Valentin Pal'shin at Ioffe Inst  <val at 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 081222 (Swift-BAT trigger #337914: Grupe et al., GCN 8691; 
Fenimore et al., GCN 8709) triggered Konus-Wind at T0=17642.534 s UT 
(04:54:02.534).

The burst light curve shows a single pulse with a duration of ~12 s.
There is a hint of the weak tail detected by the Swift-BAT (Fenimore et 
al., GCN 8709) in the K-W G1 band (~20-80 keV).

As observed by Konus-Wind the burst
had a fluence of 1.32(-0.40, +0.48)x10^-5 erg/cm2,
and a 256-ms peak flux measured from T0+4.688 s
of 2.22(-0.73, +0.87)x10^-6 erg/cm2/s
(both in the 20 keV - 1 MeV energy range).

The time-integrated spectrum of the burst
(from T0 to T0+16.640 s) can be fitted (in the 20 keV - 1 MeV
range) by GRB (Band) model for which:
the low-energy photon index is alpha = -0.67(-0.33, +0.39),
the high energy photon index beta = -2.35(-1.25, +0.30),
the peak energy Ep = 165(-29, +47) keV (chi2 = 63.0/51 dof).

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

Assuming z = 2.77 (Cucchiara et al., GCN 8713; Graham et al., GCN 8718) 
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 ~2.4x10^53 erg, 
the peak luminosity (L_iso)_max ~ 1.5x10^53 erg/s, and Ep_rest ~600 keV.

The Konus-Wind light curve of this GRB is available
at http://www.ioffe.ru/LEA/GRBs/GRB081222_T17642/