GCN Circular 12433
Subject
Konus-Wind observation of GRB 111008A
Event
Date
2011-10-09T14:58:01Z (15 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@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 GRB 111008A (Swift-BAT trigger #505054:
Saxton et al., GCN 12433; Baumgartner et al., GCN 12434)
triggered Konus-Wind at T0=79981.676s UT (22:13:01.676)
The burst light curve shows an initial pulse which
peaked at T0+0.256s and a softer weaker pulse at ~T0+30s.
A total burst duration is ~40 s.
The emission is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB111008_T79981/
As observed by Konus-Wind the burst
had a fluence of (9.0 � 0.9)x10-6 erg/cm2,
and a 256-ms peak flux, measured from T0+0.256 s,
of (1.4 � 0.3)x10-6 erg/cm2/s
(both in the 20 keV - 2 MeV energy range).
The time-integrated spectrum of the burst
(measured from T0 to T0+41.216 s) is best fitted
in the 20 keV - 2 MeV range by a simple
power-law model with index (2.02 � 0.09),
chi2 = 54.3/59 dof.
The spectrum of the initial pulse
(measured from T0 to T0+8.448 s) is best fitted
in the 20 keV - 2 MeV range by a power law
with exponential cutoff model, for which
alpha = -1.36 (-0.21, +0.24),
and Ep = 149(-28, +52) keV,
chi2 = 38.4/58 dof.
Assuming the redshift z=5.0 (Levan et al., GCN 12429;
Wiersema et al., GCN 12431) and a standard cosmology model
with H_0 = 71 km/s/Mpc, Omega_M = 0.27, Omega_Lambda = 0.73,
the isotropic energy release E_iso is (4.1 � 0.4)x10^53 erg,
the isotropic peak luminosity L_iso_max is (3.8 � 0.7)x10^53 erg/s,
and Ep_rest is 894(-168,+312) keV (the initial pulse spectrum).
All the quoted results are preliminary.
All the quoted errors are at the 90% confidence level.