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GCN Circular 23737

Subject
Konus-Wind observation of GRB 190114C
Date
2019-01-16T13:01:40Z (5 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
D. Frederiks, S. Golenetskii, R.Aptekar, A. Kozlova,
A.Lysenko,  D. Svinkin, A. Tsvetkova,  M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:

The long, very bright GRB 190114C
(Swift-BAT detection: Gropp et al., GCN 23688;
MAGIC detection: Mirzoyan et al., GCN 23701;
Fermi-GBM detection: Hamburg et al., GCN 23707;
Fermi-LAT detection: Kocevski et al., GCN 23709;
AGILE/MCAL detection: Ursi et al., GCN 23712;
Insight-HXMT/HE detection: Xiao et al., GCN 23712)
triggered Konus-Wind (KW) at T0=75422.341 s UT (20:57:02.341).

The main part of the burst light curve shows a hard-spectrum,
multi-peaked pulse, which started at ~T0 and lasting for ~6 s, followed 
by a weaker and softer pulse at ~T0+16 s.
The decaying emission tail is seen in the KW data until the end of the
trigger record at ~T0+320 s.
The emission in the main pulse is seen up to ~20 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB190114_T75422/

As observed by Konus-Wind, the main part of the burst had
a fluence of (4.83 �� 0.10)x10^-4 erg/cm2 and
a 64-ms peak energy flux, measured from T0+3.872,
of (2.40 �� 0.08)x10^-4 erg/cm2 (both in the 20 keV - 10 MeV
energy range).

The time-integrated spectrum (measured from T0 to T0+21.248 s)
is best fit in the 30 keV - 20 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.73 (-0.02,+0.02),
the high energy photon index beta = -3.17 (-0.20,+0.16),
the peak energy Ep = 646 (-16,+16) keV,
chi2 = 122/95 dof.

The spectrum near the peak count rate (measured from T0+3.584 s
to T0+4.096 s) is best fit in the 30 keV - 20 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.01 (-0.07,+0.07),
the high energy photon index beta = -2.98 (-0.22,+0.17),
the peak energy Ep = 695 (-36,+38) keV,
chi2 = 61/62 dof.

The spectrum of the extended emission (measured from T0+21 s
to T0+220 s) is best fit in the 30 keV - 20 MeV range
by a simple power law with the photon index of 2.13 (-0.11,+0.12),
chi2 = 67/99 dof.

Assuming the redshift z=0.4245 (Selsing et al., GCN 23965;
Castro-Tirado et al., GCN 23708)
and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315,
and Omega_Lambda = 0.685 (Planck Collaboration, 2014),
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is (2.4 �� 0.05)x10^53 erg,
the peak luminosity L_iso is (1.67 �� 0.05)x10^53 erg/s
(both in the 1-10000 keV rest-frame band).
With these values, GRB 190114C is within 68% prediction bands
for both 'Amati' and 'Yonetoku' relations built for the sample
of 138 long KW GRBs with known redshifts (Tsvetkova et al., ApJ 850 161, 
2017), see http://www.ioffe.ru/LEA/GRBs/GRB190114_T75422/GRB190114C.pdf

All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.
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