[vsnet-grb-info 13539] Konus-Wind observation of GRB 130610B

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14872
SUBJECT: Konus-Wind observation of GRB 130610B
DATE:    13/06/11 16:23:38 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred at 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 130610B
(IPN triangulation: Hurley at al., GCN 14868)
triggered Konus-Wind at T0=76879.093 s UT (21:21:19.093).

The light curve  from ~T0-0.5 s to ~T0+16s shows multiple pulses
with decaying spectral hardness.
The pulses form a quasi-periodic structure with the period of ~1s
during first ~5 seconds of the burst, which is followed, after T0+7s,
by the three pulses separated by ~2.7s.

A weak count rate excess in the soft energy channel (20-80 keV)
is observed from ~T0-170 s to ~T0-100 s in the instrument
background mode; however, its attribution to GRB 130610B
is not yet confirmed.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB130610_T76879/

As observed by Konus-Wind, the burst
had a fluence of (8.5 ± 0.4)x10-6 erg/cm2,
and a 64-ms peak flux, measured from T0+0.256s,
of (6.0 ± 0.5)x10-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+16.640 s)
is best fit in the 20 keV - 15 MeV range
by the cutoff power law with the following model parameters:
the photon index alpha = -1.7 ± 0.1,
the peak energy Ep = 62 ± 9 keV,
chi2 = 99/98 dof.

The 3-channel spectrum at the maximum count rate
(measured from T0+0.256 to T0+0.384 s)
can be modeled, in the 20 keV - 1.35 MeV range,
by the cutoff power law with the following model parameters:
the photon index alpha = -0.52 ± 0.08,
and the peak energy Ep = 444 ± 30 keV.

All the quoted results are preliminary.