[vsnet-grb-info 13110] Konus-Wind observation of GRB 130425A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14447
SUBJECT: Konus-Wind observation of GRB 130425A
DATE:    13/04/26 16:17:46 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred at mail.ioffe.ru>

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

The long-duration intense GRB 130425A
(Fermi-GBM detection: von Kienlin, GCN 14442;
IPN triangulation: Hurley et al., GCN 14446)
triggered Konus-Wind at T0=28280.029s UT (07:51:20.029)

The light curve shows an initial pulse, from ~T0-9 s to
~T0+15 s, followed by a bright multi-peaked structure
from ~T0+30 s to ~T0+68 s.
A total duration of the burst is ~80 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/GRB130425_T28280/

As observed by Konus-Wind, the burst
had a fluence of (5.9 ± 0.7)x10-5 erg/cm2,
and a 64-ms peak flux, measured from T0+39.808s,
of (7.1 ± 0.6)x10-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+73.216 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 = -1.29 ± 0.08,
the high energy photon index beta = -2.46 ± 0.23,
the peak energy Ep = 167 ± 17 keV,
chi2 = 107/97 dof.

The spectrum at the maximum count rate (measured from T0+33.024
to T0+40.448 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 = -1.10 ± 0.12,
the high energy photon index beta = -2.40 ± 0.36,
the peak energy Ep = 237 ± 45 keV,
chi2 = 91/97 dof.

All the quoted results are preliminary.