GCN Circular 31604
Subject
Konus-Wind detection of GRB 220209A
Event
Date
2022-02-18T17:54:23Z (4 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 long-duration GRB 220209A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 31561;
Lesage eat al., GCN Circ. 31565;
AGILE-MCAL detection: Ursi et al., GCN Circ. 31563;
GECAM detection: Zhang et al., GCN Circ. 31564;
Fermi-LAT detection: Pesce-Rollins et al., GCN Circ. 31577;
IPN triangulation: Kozyrev et al., GCN Circ. 31598)
triggered Konus-Wind at T0=82859.23 s UT (23:00:59.230).
The burst light curve shows two emission episodes.
The first one, lasting from ~T0-12 s to ~T0+98 s, and
the second episode, from ~T0+147 s to ~T0+260 s.
The total burst duration was ~272 s.
The emission is seen up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB220209_T82859/
As observed by Konus-Wind, the burst
had a fluence of 1.86(-0.32,+0.42)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+1.312 s,
of 1.12(-0.28,+0.29)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+218.624 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.83(-0.19,+0.60),
the high energy photon index beta = -1.81(-0.21,+0.16),
the peak energy Ep = 320(-162,+162) keV
(chi2 = 101/86 dof).
The spectrum near the maximum count rate
(measured from T0 to T0+7.936 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.89(-0.05,+0.06),
the high energy photon index beta = -3.17(-6.83,+0.89),
the peak energy Ep = 1675(-288,+289) keV
(chi2 = 96/86 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.