[vsnet-grb-info 13781] Konus-Wind observation of GRB 130812B

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15095
SUBJECT: Konus-Wind observation of GRB 130812B
DATE:    13/08/13 16:53:48 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 ûùàå-ûçóñåêãü GRB 130812B
(IPN triangulation: Hurley at al., GCN 15094)
triggered Konus-Wind at T0=39316.109 s UT (10:55:16.109).

The light curve shows multiple pulses from ~T0-0.5 s to ~T0+16s
followed by a weak decaying emission during the next ~15 s.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB130812_T39316/

As observed by Konus-Wind, the burst
had a fluence of (1.52 ± 0.03)x10-5 erg/cm2,
and a 64-ms peak flux, measured from T0+4.032s,
of (3.5 ± 0.3)x10-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+33.024 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 = -1.33 ± 0.07,
the peak energy Ep = 78 ± 3 keV,
chi2 = 90/98 dof.

The time-averaged spectrum of the bright phase of the burst
(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 = -1.04 ± 0.07,
the peak energy Ep = 90 ± 2 keV,
chi2 = 75/97 dof.

All the quoted results are preliminary.