TITLE:   GCN CIRCULAR
NUMBER:  31537
SUBJECT: Konus-Wind detection of GRB 220128A
DATE:    22/01/31 17:46:00 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin,
A. Tsvetkova,  M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:

The long GRB 220128A (IPN localization: Kozyrev et al., GCN 31536)
triggered Konus-Wind (KW) at T0=11896.619 s UT (03:18:16.619).

The burst light curve shows a multi-peaked structure,
which starts at ~T0-10 s and has a total duration of ~47 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/GRB220128_T11896/

As observed by Konus-Wind, the burst had
a fluence of (3.2 ± 0.7)x10^-5 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 10.496 s,
of (5.9 ± 1.1)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum (measured from T0 to T0+24.832 s)
is best fit in the 20 keV - 20 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.92 (-0.18,+0.28),
the high energy photon index beta = -2.19 (-1.92,+0.32),
the peak energy Ep = 406 (-135,+174) keV,
chi2 = 88/97 dof.

All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.