TITLE: GCN CIRCULAR NUMBER: 40177 SUBJECT: GRB 250407A: rest-frame energetics from Konus-Wind observation DATE: 25/04/19 14:12:21 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: Assuming the spectrum and the observer-frame energetics of the very bright GRB 250407A (GCN 40104) measured by Konus-Wind (GCN 40121); the redshift z=1.36 (Schneider et al., GCNs 40175); 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 (7.86 ± 0.20)x10^53 erg, the isotropic peak luminosity L_iso to (1.66 ± 0.06)x10^54 erg/s, the rest-frame peak energy of the time-integrated spectrum Ep,i,z to (1530 ± 110) keV, and the rest-frame peak energy at the peak of the emission Ep,p,z to (1970 ± 250) keV. With the obtained estimates, GRB 250407A is among 10 most luminous (and 50 most energetic) GRBs detected by Konus-Wind. The burst is consistent with 68% prediction bands for both 'Amati' and 'Yonetoku' relations derived 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/GRB250407_T56895/GRB250407A_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/40177. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...