GCN Circular 46268

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

GRB 261113A (SVOM detection: Saccardi et al., GCN 46244
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triggered Konus-Wind (KW) at T0=52263.795 s UT (14:31:03.795).

The burst light curve shows a mult-peaked structure with the total duration of ~7 s.
The emission is seen up to ~700 keV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB261113_T52263/

As observed by Konus-Wind, the burst had the total fluence
of (3.51 ± 0.61)x10^-6 erg/cm^2 and a 16-ms peak energy flux,
measured from T0, of (1.36 ± 0.24)x10^-6 erg/cm^2/s
(both in the 20 keV - 10 MeV energy range).

The spectrum of the burst (measured from T0 to T0+8.448 s)
is best fitted in the 20 keV - 15 MeV range by a power law with exponential
cutoff (CPL) model dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.81 (-0.30, + 0.33) and Ep = 106(-9,+10) keV, PGstat = 49/60 dof.
Fitting this spectrum by a Band GRB function yields the same values
of alpha and Ep, and an upper limit on the high energy photon index beta of -3.1

Assuming the redshift z=3.580 (Saccardi et al., GCN 46261
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and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315,
and Omega_Lambda = 0.685 (Planck Collaboration, 2014),
we estimate the burst isotropic energy release E_iso to (9.49 ± 1.65)x10^52 erg,
the isotropic peak luminosity L_iso to (1.68 ± 0.29)x10^53 erg/s, and
the rest-frame peak spectral energy Ep,z to (485 ± 43) keV.
With the obtained estimates, GRB 261113A is consistent with 68% prediction bands
for both 'Amati' and  'Yonetoku' relations for the sample of >300 long KW GRBs
with known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 2021),
see http://www.ioffe.ru/LEA/GRBs/GRB261113_T52263/GRB261113A_rest_frame.pdf

All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.