[vsnet-grb-info 5267] Konus-Wind observation of GRB 071020

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6960
SUBJECT: Konus-Wind observation of GRB 071020
DATE:    07/10/21 13:31:43 GMT
FROM:    Valentin Pal'shin at Ioffe Inst  <val at mail.ioffe.ru>

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

The long GRB 071020 (Swift-BAT trigger #294835:
Holland et al., GCN 6949, Tueller et al., GCN 6954) triggered
Konus-Wind at T0=25346.637 s UT (07:02:26.637).

The burst light curve shows a multipeaked structure
with a duration of ~3.5 s.
As observed by Konus-Wind the burst
had a fluence of 7.71(-4.76, +0.39)x10^-6 erg/cm2,
and a 64-ms peak flux measured from T0+2.416 s
of 6.04(-3.88, +1.12)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+8.448 s) is well 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 = 0.65(-0.32, +0.27)
and Ep = 322(-53, +80) keV (chi2 = 64.4/61 dof).
Fitting by GRBM (Band) model yields only an upper limit
on the high energy photon index: beta < -1.97.
All the quoted errors are at the 90% confidence level.

Assuming z = 2.145 (Jakobsson et al., GCN 6952)
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 ~8x10^52 erg, and
the maximum bolometric luminosity is (L_iso)_max ~2x10^53 erg/s.

The Konus-Wind light curve of this GRB is available
at http://www.ioffe.rssi.ru/LEA/GRBs/GRB071020_T25346/