TITLE:   GCN CIRCULAR
NUMBER:  36041
SUBJECT: LXT 240402A/GRB 240402B: rest-frame energetics from Konus-Wind observation
DATE:    24/04/06 14:54:45 GMT
FROM:    Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>

A. Ridnaia, D. Frederiks, A. Lysenko, 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 GRB 240402B
measured by KW (GCN 36028); the redshift of the probable host galaxy
z=0.047 (Xu et al., GCN 36016; Levan et al., GCN 36025; Xue at al., GCN 36034);
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 (4.06 ± 0.27)x10^49 erg,
the isotropic peak luminosity L_iso to (2.85 ± 0.38)x10^49 erg/s,
the rest-frame peak energy of the time-integrated spectrum Ep,i,z to (90 ± 5) keV.

With the obtained estimates, GRB 240402B is a low-luminosity outlier
in 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/GRB240402_T31668/GRB240402B_rest_frame.pdf

All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.