TITLE:   GCN CIRCULAR
NUMBER:  40948
SUBJECT: Konus-Wind detection of GRB 250702F
DATE:    25/07/04 13:22:06 GMT
FROM:    Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>

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

The long-duration GRB 250702F (Fermi-GBM detection:
The Fermi GBM team, GCN 40892; Mukherjee & Meegan, GCN 40927;
Swift detection: Klingler et al., GCN 40894)
triggered Konus-Wind (KW) at T0=76042.205 s UT (21:07:22.205).

The burst shows multiple emission pulses and has a total duration of ~46 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/GRB250702_T76042/

As observed by Konus-Wind, the burst had
a fluence of (1.60 ± 0.25)x10^-5 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 0.512 s,
of (5.02 ± 1.15)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).

Modeling the time-integrated spectrum of the burst
by a power law with exponential cutoff (CPL) model
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
yields alpha = -1.47 (-0.10, + 0.10) and Ep = 480(-130,+250) keV.

The spectrum near the peak count rate (measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 15 MeV range by a GRB (Band) function
with the following model parameters:
the low-energy photon index alpha = -1.22 (-0.12,+0.17),
the high energy photon index beta = -2.20 (-7.8,+0.29),
the peak energy Ep = 505 (-155,+326) keV,
chi2 = 85/94 dof.

Assuming the redshift z=1.520 (de Ugarte Postigo et al., GCN 40896)
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 (9.9 ± 1.5)x10^52 erg,
the isotropic peak luminosity L_iso to (7.8 ± 1.8)x10^52 erg/s, and
the rest-frame peak spectral energy Ep,z to ~1250 keV.
With the obtained estimates, GRB 250702F is consistent with 90% prediction bands
of 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/GRB250702_T76042/GRB250702F_rest_frame.pdf

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