TITLE:   GCN CIRCULAR
NUMBER:  27228
SUBJECT: Konus-Wind observation of GRB 200219C
DATE:    20/02/26 19:03:50 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

D. Svinkin, S. Golenetskii, R. Aptekar, 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 200219C
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 27145;
Hamburg et al., GCN Circ. 27155;
Fermi-LAT detection: Dirirsa et al., GCN Circ. 27151;
CALET-GBM detection: Sugita et al., GCN Circ. 27163)
triggered Konus-Wind at T0=86229.162 s UT (23:57:09.162).

The burst light curve shows a bright peak which starts at ~T0-3.4 s
and has a duration of ~9.8 s, followed by a weaker emission
seen up to ~T0+23 s. Total burst duration is ~27 s.
The emission is seen up to ~4 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB200219_T86229

As observed by Konus-Wind, the burst
had a fluence of 1.87(-0.11,+0.13)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+3.488 s,
of 5.40(-1.08,+1.23)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+29.952 s)
is best fit in the 20 keV - 2 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.08(-0.12,+0.12)
and Ep = 209(-21,+27) keV (chi2 = 60/61 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.6
(chi2 = 60/60 dof).

The spectrum near the maximum count rate
(measured from T0+0.256 to T0+5.376 s)
is best fit in the 20 keV - 4 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.83(-0.10,+0.12),
the high energy photon index beta = -3.58(-6.42,+0.82),
the peak energy Ep = 234(-22,+20) keV
(chi2 = 62/75 dof).

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