TITLE: GCN CIRCULAR NUMBER: 39116 SUBJECT: Konus-Wind detection of GRB 250129A DATE: 25/02/01 17:29:52 GMT FROM: Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru> D. Frederiks, A.Lysenko, A. Ridnaya, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The long GRB 250129A (Swift detection: Beardmore et al., GCN 39066) was detected by Konus-Wind (KW) in the waiting mode. A Bayesian block analysis of the KW waiting mode data in the 20-400 keV band reveals a >6 sigma count rate increase in the interval from T0-66 s to T0+208 s where T0 = T0(BAT) = 04:45:09 UT. The KW light curve of this burst is available at http://www.ioffe.ru/LEA/GRBs/GRB250129A/ 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 = -1.74 (-0.07, + 0.07) and Ep = 66(-8,+8) keV. In the 10 keV -10 MeV band, standard for the KW analysis, the burst fluence is (6.71 ± 0.14)x10^-6 erg/cm^2 and the 2.944 s peak energy flux is (1.46 ± 0.18)x10^-7 erg/cm^2/s. Assuming the redshift z=2.151 (Schneider et al., GCN 39071) 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 (7.7 ± 0.2)x10^52 erg, the isotropic peak luminosity L_iso to (5.3 ± 0.7)x10^51 erg/s, and the rest-frame peak spectral energy Ep,z to (207 ± 22) keV. With the obtained estimates, GRB 250129A is consistent with 68% prediction bands of '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/GRB250129A/GRB250129A_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/39116. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...