GCN Circular 31622
Subject
Konus-Wind observation of GRB 220219A
Event
Date
2022-02-21T17:12:32Z (4 years ago)
From
Anastasia Tsvetkova at Ioffe Institute <tsvetkova@mail.ioffe.ru>
A. Tsvetkova, D. Frederiks, A. Lysenko, A. Ridnaia, D. Svinkin,
M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report:
The long-duration GRB 220219A
(Fermi-GBM detection: The Fermi GBM team, GCN 31609;
AGILE/MCAL detection: Ursi at al., GCN31611;
IPN triangulation: Kozyrev et al., GCN 31621)
triggered Konus-Wind at T0=40894.695 s UT (11:21:34.695).
The burst light curve shows a multi-peaked structure
which starts at ~T0-0.4 s and has a total duration of~76.6 s.
The emission is seen up to ~15 MeV.
As observed by Konus-Wind, the burst
had a fluence of 5.75(-2.01,+1.80)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0+3.792 s,
of 1.08(-0.21,+0.21)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+80.384 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.01(-0.39,+0.52),
the high energy photon index beta = -1.86(-1.11,+0.20),
the peak energy Ep = 379(-155,+830) keV,
chi2 = 93/97 dof.
The spectrum near the peak count rate
(measured from T0 to T0+6.656 s)
is best fit in the 20 keV - 15 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with�� alpha = -1.03(-0.10,+0.11),
and Ep = 480(-57,+73) keV (chi2 = 97/98 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.29 (chi2 = 96.1/97 dof).
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB220219_T40894/
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.