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GCN Circular 31802

Subject
Konus-Wind observation of GRB 220320A
Date
2022-03-28T16:58:44Z (2 years ago)
From
Anastasia Tsvetkova at Ioffe Institute <tsvetkova@mail.ioffe.ru>
A. Tsvetkova,�� D. Frederiks, D. Svinkin,
M. Ulanov, A. Lysenko, A. Ridnaia and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration, bright GRB 220320A
(AstroSat CZTI detection: Gopalakrishnan et al., GCN 31779;
IPN triangulation: Kozyrev et al., GCN 31783)
triggered Konus-Wind at T0=16796.141 s UT (04:39:56.141).

The burst light curve shows a multi-peaked structure
which starts at ~T0-18.8 s and has a total duration of~52.8 s
The emission is seen up to ~20 MeV.

As observed by Konus-Wind, the burst
had a fluence of 6.05(-0.50,+0.52)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0+4.048 s,
of 2.50(-0.34,+0.34)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(measured from T0 to T0+20.480 s)
is best fit in the 20 keV - 20 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.84(-0.09,+0.10),
the high energy photon index beta = -2.27(-0.15,+0.11),
the peak energy Ep = 224(-21,+24) keV,
chi2 = 100/97 dof.

The spectrum near the peak count rate
(measured from T0 to T0+4.352 s)
is best fit in the 20 keV - 20 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.43(-0.11,+0.12),
the high energy photon index beta = -2.31(-0.17,+0.13),
the peak energy Ep = 311(-29,+33) keV,
chi2 = 67/86 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB220320_T16796/

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