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GCN Circular 22227

Konus-Wind observation of GRB 171205A
2017-12-10T17:31:55Z (6 years ago)
Dmitry Frederiks at Ioffe Institute <>
D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov,
D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline,
on behalf of the Konus-Wind team, report:

The long GRB 171205A (Swift-BAT trigger #794972: (D'Elia et al.,
GCN  22177; Barthelmy et al., GCN 22184; T0(BAT)= 07:20:43.893 UT)
was detected by Konus-Wind (KW) in the waiting mode.

A bayesian block analysis of the KW waiting mode data reveals a count
rate increase in the interval from ~T0(BAT)-50 s to ~T0(BAT)+95 s.
The detection significance in the combined G1+G2 light curve
(25-360 keV) is ~10 sigma (95 s scale) while no statistically
significant emission has been detected in the G3 band (360-1470 keV).

The KW light curve of this burst is available at

The time-averaged 3-channel spectrum, measured from T0(BAT)-48.743 s
to T0(BAT)+42.521 s, is well fit by a simple power-law (PL) model
with the PL index 2.0 �� 0.18, chi2 = 0.88 for 1 dof.
The burst fluence in the 20-1500 keV band is (7.8 �� 1.6)x10^-6 erg/cm^2.

Assuming z = 0.0368 (Izzo et al., GCN 22180) and a standard cosmology
model with H_0 = 70 km/s/Mpc, Omega_M = 0.30, and Omega_Lambda = 0.70, 
the burst isotropic energy release E_iso is 2.4x10^49 erg (20-1500 keV,
observer frame).

All the quoted errors are estimated at the 1 sigma confidence level.
All the presented results are preliminary.
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