GCN Circular 31553
Subject
Konus-Wind detection of GRB 220203A
Date
2022-02-05T15:37:19Z (2 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
D. Svinkin, D. Frederiks, M. Ulanov, A. Tsvetkova,
A. Lysenko, A. Ridnaia, and T. Cline
on behalf of the Konus-Wind team, report:
The short-duration GRB 220203A
(IPN triangulation: Svinkin et al., GCN Circ. 31549;
Swift/BAT-GUANO detection: Tohuvavohu et al., GCN Circ. 31550;
GECAM detection: Guo et al., GCN Circ. 31552)
triggered Konus-Wind at T0=76534.783 s UT (21:15:34.783).
The burst light curve shows a multi-peaked structure
which starts at ~T0-0.1 s and has a total duration of ~0.3 s.
The emission is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB220203_T76534/
As observed by Konus-Wind, the burst
had a fluence of 1.02(-0.26,+0.38)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0-0.072 s,
of 8.81(-3.98,+5.24)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+0.256 s)
is best fit in the 20 keV - 5 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.60(-0.52,+0.87)
and Ep = 408(-159,+377) keV (chi2 = 7/18 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -1.9
(chi2 = 8/17 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.