LIGO/Virgo/KAGRA S241125n: Upper limits from Konus-Wind observations

Konus-Wind (KW) was observing the whole sky at the time of the LIGO/Virgo/KAGRA event S241125n (2024-11-25 01:01:16.780 UTC, hereafter T0; LIGO/Virgo/KAGRA Collaboration GCN Circ. 38305, 38309, 38312, 38313, 38315). No triggered or waiting-mode KW GRBs happened between ~2 days before and ~15 hours after T0 (the current available data). Using waiting-mode data within the interval T0 +/- 200 s, we found no significant (> 5 sigma) excess over the background in both KW detectors on temporal scales from 2.944 s to 100 s. We estimate an upper limit (90% conf.) on the 20 - 1500 keV fluence to 7.5x10^-7 erg/cm^2 for a burst lasting less than 2.944 s and having a typical KW short GRB spectrum (an exponentially cut off power law (CPL) with alpha =-0.5 and Ep=500 keV) and to 4.7x10^-7 erg/cm^2 for a burst having spectrum similar to that of GRB 170817A (a CPL with alpha =-0.62 and Ep=185 keV). For a typical long GRB spectrum (the Band function with alpha=-1, beta=-2.5, and Ep=300 keV), the corresponding limiting peak flux is 2.2x10^-7 erg/cm^2/s (20 - 1500 keV, 2.944 s scale). All the quoted values are preliminary.