GCN Circular 7854

S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and
T. Cline on behalf of the Konus-Wind team report:

The bright GRB 080605 (Swift-BAT trigger #313299: Sbarufatti et al., GCN
7828
Not found
 
 
, Cummings et al., GCN 7839
Not found
 
 
) triggered Konus-Wind at T0=85682.336 s 
UT (23:48:02.336).

The burst light curve shows a multipeaked structure with a total 
duration of ~20s.

As observed by Konus-Wind the burst
had a fluence of 3.02(-0.12, +0.13)x10^-5 erg/cm2,
and a 16-ms peak flux measured from T0+7.984 s
of (1.60 +/- 0.33)x10^-5 erg/cm2/s
(both in the 20 keV - 2 MeV energy range).

The time-integrated spectrum of the burst
(from T0 to T0+18.944 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 = -1.03 +/- 0.07,
and Ep = 252(-17, +20) keV (chi2 = 57.2/61 dof).
Fitting by GRBM (Band) model yields:
the low-energy photon index is alpha = -1.02 +/- 0.08,
the high energy photon index beta < -2.75,
the peak energy Ep =  246(-18, +23) keV (chi2 = 56.7/60 dof).

The spectrum of the most intense peak (from T0+7.168 s to T0+8.960 s)
is well fitted (in the 20 keV - 2 MeV range)
by a power law with exponential cutoff model
with alpha =  -0.94 +/- 0.10
and Ep = 333(-34, +42) keV (chi2 = 60.6/54 dof).
Fitting by GRBM (Band) model yields:
the low-energy photon index is alpha = -0.87(-0.12, +0.13),
the high energy photon index beta = -2.58(-0.84, +0.31),
the peak energy Ep =  297(-40, +46) keV (chi2 = 56.6/53 dof).

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

Assuming z = 1.640 (Jakobsson et al., GCN 7832
Not found
 
 
) and a standard
cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.27, Omega_\Lambda =
0.73, the isotropic energy release is E_iso ~2.1x10^53 erg,
the maximum luminosity is (L_iso)_max ~3.0x10^53 erg/s, and
Ep_rest ~660 keV.

The Konus-Wind light curve of this GRB is available
at http://www.ioffe.rssi.ru/LEA/GRBs/GRB080605_T85682/