TITLE:   GCN CIRCULAR
NUMBER:  44881
SUBJECT: Konus-Wind detection of GRB 260607B
DATE:    26/06/09 11:26:57 GMT
FROM:    Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>

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

The long-duration GRB 260607B
(Fermi-GBM detection: Fermi-GBM team, GCN 44859;
Neights & Palafox, GCN 44861;
Fermi-LAT detection: Holzmann Airasca et al., GCN 44860;
AstroSat CZTI detection: Harsha et al., GCN 44871;
GECAM-B detection: Wang et al., GCN 44880)
triggered Konus-Wind at T0=47968.353 s UT (13:19:28.353).

The burst light curve shows a bright multipeaked structure
which starts at ~T0-6.8 s and ends at ~T0+50 s, 
which is followed by a weaker decaying  emission with a 
'bump' around ~T0+190 s. The total duration of the 
burst is ~209.8 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/GRB260607_T47968/

As observed by Konus-Wind, the burst
had the total fluence of 4.55(-0.09,+0.09)x10^-4 erg/cm2,
and the 64-ms peak flux, measured from T0+29.456 s,
of 3.33(-0.27,+0.27)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+57.600 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.88(-0.02,+0.02),
the high energy photon index beta = -2.87(-0.14,+0.11),
the peak energy Ep = 622(-15,+16) keV
(chi2 = 103/97 dof).

The spectrum near the maximum count rate
(measured from T0+29.184 to T0+30.720 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.74(-0.06,+0.06),
the high energy photon index beta = -2.80(-0.37,+0.22),
the peak energy Ep = 686(-51,+55) keV
(chi2 = 48/62 dof).

All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.