S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks,
P. Oleynik, M. Ulanov and T. Cline on behalf of the Konus-Wind and
Konus-A teams report:
The long bright GRB 070508 (Swift-BAT trigger #278854:
Grupe et al., GCN 6383; Barthelmy et al., GCN 6390), triggered
Konus-Wind at T0=15502.779 s UT (04:18:22.779).
This burst also triggered Konus-A at T0=15503.790 s UT
The burst started at T-T0 ~-13 s and had a duration of ~40 s.
As observed by Konus-Wind the burst
had a fluence of 3.97(-0.23, +0.07)x10^-5 erg/cm2,
and a 64-ms peak flux measured from T0+8.832 s
8.30(-1.11, +1.03)x10^-6 erg/cm2/s
(both in the 20 keV - 1 MeV energy range).
The burst shows strong spectral evolution.
The time-integrated spectrum of the burst
(from T0 to T0+27.904 s) can be fitted (in the 25 keV - 1 MeV range)
by a power law with exponential cutoff model:
dN/dE ~ E^(-alpha)*exp(-E*(2-alpha)/Ep)
with alpha = 0.81 +/- 0.07
and Ep = 188 +/- 8 keV (chi2 = 65/52 dof).
Assuming z = 0.82 (Jakobsson et al., GCN 6398)
and a standard cosmology model with H_0 = 70 km/s/Mpc,
Omega_M = 0.3, Omega_\Lambda = 0.7,
the isotropic bolometric energy release is E_iso ~7.0x10^52 erg, and
the maximum bolometric luminosity is (L_iso)_max ~1.1x10^53 erg/s.
All the quoted errors are at the 90% confidence level.
The Konus-Wind light curve of this GRB is available