TITLE: GCN CIRCULAR NUMBER: 44647 SUBJECT: Konus-Wind detection of GRB 260515A DATE: 26/05/16 19:07:11 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: A long-duration GRB 260515A (SVOM detection: Brunet et al., GCN 44622) was detected by Konus-Wind (KW)in the waiting mode at T0=T0(KW)~19:08:19UT. A Bayesian block analysis of the KW data in the 20-1500 keV band reveals a ~8 sigma count rate increase in the interval from ~T0+0.4 s to ~T0+9.3 s from the SVOM detection time. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB260515A/ 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 = -1.37 (-0.17, + 0.17) and Ep = 95(-9,+10) keV. In the 10 keV -10 MeV band, standard for the KW analysis, the burst fluence is (7.70 ± 0.81)x10^-6 erg/cm^2 and the 2.944 s peak energy flux is (1.47 ± 0.22)x10^-7 erg/cm^2/s. Assuming the redshift z=0.764 (Malesani et al., GCN 44629) 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 (1.25 ± 0.15)x10^52 erg, the isotropic peak luminosity L_iso to (5.70 ± 0.85)x10^50 erg/s, and the rest-frame peak spectral energy Ep,z to (168 ± 18) keV. With the obtained estimates, GRB 260515A is consistent with 68% prediction bands of both 'Amati' relation and 90% prediction bands of 'Yonetoku' relation 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/GRB260515A/GRB260515A_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/44647. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...