TITLE:   GCN CIRCULAR
NUMBER:  32172
SUBJECT: Konus-Wind detection of GRB 220601A
DATE:    22/06/06 17:24:42 GMT
FROM:    Alexandra Lysenko at Ioffe Institute  <alexandra.lysenko@mail.ioffe.ru>

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

The long-duration GRB 220601A
(IPN triangulation: Kozyrev et al., GCN Circ. 32163)
triggered Konus-Wind at T0=22766.297 s UT (06:19:26.297).

The burst light curve shows a multipeaked structure
which starts at ~T0-42.5 s and has a total duration of ~82.5 s.
The emission is seen up to ~3 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB220601_T22766/

As observed by Konus-Wind, the burst
had a fluence of 2.64(-0.16,+0.17)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+3.056s,
of 6.19(-1.55,+1.57)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+41.216 s)
is best fit in the 28 keV - 5 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.79(-0.17,+0.18)
and Ep = 195(-17,+21) keV (chi2 = 58/71 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 = 57/70 dof).

The spectrum near the maximum count rate
(measured from T0+0.256 to T0+8.448 s)
is best fit in the 20 keV - 5 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.74(-0.16,+0.17),
the high energy photon index beta = -2.81(-2.84,+0.34),
the peak energy Ep = 220(-24,+31) keV
(chi2 = 62/70 dof).

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