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GCN Circular 20197

Subject
Konus-Wind observation of GRB 161117A
Date
2016-11-18T13:12:24Z (8 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, A. Tsvetkova, A. Lysenko, A. Kozlova, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 161117A
(Swift-BAT observation: Cummings et al., GCN Circ. 20179;
Fermi-GBM detection: Mailyan & Goldstein, GCN Circ. 20192)
triggered Konus-Wind at T0=5738.426 s UT (01:35:38.426).

The burst light curve shows  three bright emission peaks in the interval 
from ~T0-7 s to ~T0+130 s.
The emission is seen up to ~1 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB161117_T05738/

As observed by Konus-Wind, the burst
had a fluence of 2.41(-0.14,+0.15)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0-0.342 s,
of 1.94(-0.77,+0.78)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+123.136 s)
is best fit in the 20 keV - 1 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.86(-0.33,+0.36)
and Ep = 69(-7,+6) keV (chi2 = 40/47 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta <-3.5
(chi2 =40/46 dof).

The spectrum near the maximum count rate
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 1 MeV range
by a power law with exponential cutoff model:
with  alpha = -0.56(-0.42,+0.52)
and Ep = 139(-20,+27) keV (chi2 = 49/47 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.6
(chi2 = 49/46 dof).

Assuming the redshift z=1.549 (Malesani et al., GCN 20180)
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 ~1.3x10^53 erg,
the peak luminosity L_iso is ~3.0x10^52 erg/s,
and the rest-frame peak energy of the time-integrated spectrum,
Ep,i, is ~176 keV.

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
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