TITLE:   GCN CIRCULAR
NUMBER:  21246
SUBJECT: Konus-Wind observation of GRB 170607B
DATE:    17/06/11 13:36:09 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov,
D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline,
on behalf of the Konus-Wind team, report:

The long GRB 170607B (AstroSat CZTI detection: Sharma et al., GCN 21232;
Fermi GBM detection: Hamburg et al., GCN 21238;
IPN triangulation: Hurley et al., GCN 21242)
triggered Konus-Wind at T0=81725.036 s UT (22:42:05.036).

The burst light curve shows a bright, multi-peaked pulse
which started at ~T0-9 s an had a total duration of ~35 s.
A weak count rate increase is also visible around ~T0+100 s
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst had a fluence of
(7.2 ± 0.8)x10^-5 erg/cm2 and a 64-ms peak energy flux,
measured from T0+18.752 s of (8.1 ± 1.2)x10^-6 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+22.528 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.77 (-0.07,+0.08),
the high energy photon index beta = -2.87 (-1.27,+0.40),
the peak energy Ep = 512 (-50,+49) keV,
chi2 = 105/97 dof.

The spectrum near the peak count rate (measured from T0+14.336
to T0+22.528 s) is best fit in the 20 keV - 5 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.58 (-0.32,+0.38),
the high energy photon index beta = -2.22 (-1.17,+0.22),
the peak energy Ep = 244 (-51,+103) keV,
chi2 = 70/72 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170607_T81725/

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