GCN Circular 32237

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

The short-duration GRB 220617A
(Fermi-GBM detection: Fermi GBM Team, GCN Circ 32209;
Wood, GCN Circ 32224;
Fermi-LAT detection: Di Lalla et al., GCN Circ 32212;
IPN triangulation: Kozyrev et al., GCN Circ 32220)
triggered Konus-Wind at T0=66669.24 s UT (18:31:09.240).

The burst light curve shows a multipeaked structure,
which starts at ~T0-0.2 s and has a total duration of ~0.5 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/GRB220617_T66669/

As observed by Konus-Wind, the burst
had a fluence of 6.53(-1.15,+1.34)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0-0.028 s,
of 3.31(-1.27,+1.36)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+0.256 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = 0.02(-0.40,+0.57)
and Ep = 1384(-341,+504) keV (chi2 = 34/40 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.0
(chi2 = 33/39 dof).

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