Konus-Wind detection of GRB 240811A

The long-duration GRB 240811A (Swift detection: Page & Gupta, GCN 37136; Lien et al., GCN 37155) was detected by Konus-Wind (KW) in the waiting mode. A Bayesian block analysis of the KW waiting mode data in the 20-300 keV band reveals a >18 sigma count rate increase in the interval from T0-34.908 s to T0+35.748 s where T0 = T0(BAT) = 14:07:33.190 UT. The KW light curve of this burst is available at http://www.ioffe.ru/LEA/GRBs/GRB240811A/ Modeling a time-integrated spectrum of the burst (from T0-34.908 s to T0+35.748 s) by a power law with exponential cutoff (CPL) model dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep): yields alpha = -1.22 (-0.27, + 0.80) and Ep = 126(-33,+51) keV. The total burst fluence is 4.65(-0.30,+1.35)x10^-6 erg/cm^2, and the 2.944 s peak energy flux, measured from T0+3.364 s, is 2.43(-0.33,+0.76)x10^-7 erg/cm^2. (both in the 20 keV - 10 MeV energy range). All the quoted errors are estimated at the 68% confidence level. All the presented results are preliminary.