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.