[vsnet-grb-info 13523] Konus-Wind observation of GRB 130609B

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14856
SUBJECT: Konus-Wind observation of GRB 130609B
DATE:    13/06/10 16:22:33 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 intense GRB 130609B
(Swift-BAT trigger 557828: Krimm, et al., GCN 14841)
triggered Konus-Wind at T0=77916.818 s UT (21:38:36.818)

The light curve consists of two major emission episodes:
the first one with a bright multi-peaked structure from ~T0-30 s to ~T0+55 s,
and the second, much weaker and softer episode, from ~T0+170 s to ~T0+210 s.
The emission is seen up to 7 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB130609_T77916/

As observed by Konus-Wind, the burst
had a fluence of (9.4 ± 0.7)x10-5 erg/cm2,
and a 64-ms peak flux, measured from T0+3.712 s,
of (9.5 ± 0.6)x10-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the first emission episode
(measured from T0 to T0+54.528 s)
is best fit in the 20 keV - 18 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.84 ± 0.05,
the high energy photon index beta = -2.39 ± 0.15,
the peak energy Ep = 397 ± 26 keV,
chi2 = 97/97 dof.

The time-averaged spectrum of the second emission episode
(measured from T0+169.216 to T0+210.176 s)
is best fit in the 20 keV - 18 MeV range
by the cutoff power law with the following model parameters:
the photon index alpha = -1.64 ± 0.21,
the peak energy Ep = 198 ± 105 keV,
chi2 = 93.7/98 dof.

The spectrum at the maximum count rate
(measured from T0 to T0+6.656 s)
is best fit in the 20 keV - 18 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.70 ± 0.07,
the high energy photon index beta = -3.0 ± 0.3,
the peak energy Ep = 740 ± 90 keV,
chi2 = 105/97 dof.


All the quoted results are preliminary.