GCN Circular 17587
Subject
Konus-Wind observation of GRB 150314A
Event
Date
2015-03-15T12:48:21Z (11 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration, very intense GRB 150314A
(Swift-BAT trigger #634795: Hagen et al., GCN 17572; Cummings et al., GCN 17581;
Fermi-LAT detection: Axelsson et al., GCN 17576;
Fermi-GBM observation: Yu, GCN 17579)
triggered Konus-Wind at T0=17691.727 s UT (04:54:51.727).
The KW light curve shows a bright multi-peaked pulse
with a duration of ~14 s.
The emission is visible up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150314_T17691/
As observed by Konus-Wind, the burst had a fluence
of 9.1(-0.4,+0.4)x10^-5 erg/cm2, and a 64-ms peak flux,
measured from T0+1.344 s, of 2.2(-0.1,+0.1)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum (measured from T0 to T0+12.288 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 = -0.79 (-0.04,+0.04),
the high energy photon index beta = -2.91 (-0.28,+0.18),
the peak energy Ep = 350 (-17,+17) keV,
chi2 = 142/97 dof.
The spectrum near the peak count rate
(measured from T0+0.256 to T0+2.048 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 = -0.37 (-0.08,+0.09),
the high energy photon index beta = -2.81 (-0.27,+0.18),
the peak energy Ep = 348 (-27,+27) keV,
chi2 = 134/94 dof.
Assuming the redshift z=1.758 (de Ugarte Postigo et al., GCN 17583)
and a standard cosmology model with H_0 = 70 km/s/Mpc,
Omega_M = 0.27, and Omega_Lambda = 0.73,
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is ~6.9x10^53 erg,
the peak luminosity L_iso is ~4.6x10^53 erg/s,
and the rest-frame peak energy of the time-integrated spectrum,
Ep,i, is ~965 keV.
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.