[vsnet-grb-info 25387] LIGO/Virgo S200311bg: Upper limits from Konus-Wind observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  27487
SUBJECT: LIGO/Virgo S200311bg: Upper limits from Konus-Wind observations
DATE:    20/04/03 22:20:06 GMT
FROM:    Anna Ridnaia at Ioffe Institute  <ridnaia at mail.ioffe.ru>

A. Ridnaia, S. Golenetskii, R.Aptekar, D. Frederiks,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, 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 event S200311bg (2020-03-11 11:58:53.398 UTC, hereafter T0;
LIGO/Virgo Collaboration GCN Circ. 27358).

No triggered KW GRBs happened between ~3 hours before and ~1.5 days
after T0. Using waiting-mode data within the interval T0 +/- 100 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 8.2x10^-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 with
alpha =-0.5 and Ep=500 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 2.4x10^-7 erg/cm^2/s (20 - 1500 keV, 2.944 s scale).

All the quoted values are preliminary.