GCN Circular 38321
Subject
LIGO/Virgo/KAGRA S241125n: Upper limits from Konus-Wind observations
Date
2024-11-26T12:20:39Z (a year ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
Via
Web form
A.Ridnaia, D. Frederiks, A.Lysenko, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
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.