TITLE:   GCN CIRCULAR
NUMBER:  15413
SUBJECT: Konus-Wind observation of GRB 131030A
DATE:    13/10/31 10:40:11 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf
of the Konus-Wind team, report:

The long-duration GRB 131030A
(Swift-BAT trigger 576238: Troja, et al., GCN 15402)
triggered Konus-Wind at T0=75377.811 s UT (20:56:17.811).

The burst light curve shows a multi-peaked pulse from
~T0-3 s till ~T0+25 s.
The emission is seen up to ~10 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB131030_T75377/

As observed by Konus-Wind, the burst
had a fluence of (6.6 ± 0.4)x10-5 erg/cm2,
and a 64-ms peak flux, measured from T0+11.648 s,
of (1.0 ± 0.1)x10-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum (measured from T0 to T0+27.904 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.71 ± 0.12,
the high energy photon index beta = -2.95 ± 0.28,
the peak energy Ep = 177 ± 10 keV,
chi2 = 76/96 dof.

Assuming the redshift z=1.293 (Xu, et al., GCN 15407;
de Ugarte Postigo, et al., GCN 15408),
and a standard cosmology model with H_0 = 70 km/s/Mpc,
Omega_M = 0.27, and Omega_Lambda = 0.73,
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is (3.0 ± 0.2)x10^53 erg,
the peak luminosity L_iso is (1.0 ± 0.1)x10^53 erg/s,
and the rest-frame peak energy Ep,i = (406 ± 22) keV

All the quoted values are preliminary.