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. View this GCN Circular online at https://gcn.nasa.gov/circulars/40948. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...