GCN Circular 27135

M. Ageron (CPPM/CNRS), B. Baret (APC/CNRS), A. Coleiro (APC/Universite de Paris), M. Colomer (APC/Universite de Paris), D. Dornic (CPPM/CNRS), A. Kouchner (APC/Universite de Paris), T. Pradier (IPHC/Universite de Strasbourg) report on behalf of the ANTARES Collaboration:


Using on-line data from the ANTARES detector, we have performed a follow-up analysis of the
recently reported LIGO/Virgo S200219ac event using the 90% contour of the Initial Bayestar probability
map provided by the GW interferometers (GCN#27130
Not found
 
 
 <https://gcn.gsfc.nasa.gov/gcn3/27130.gcn3
Not found
 
 
>). The ANTARES visibility at the time of the
alert, together with the 50% and 90% contours of the probability map are shown at http://antares.in2p3.fr/GW/S200219ac_Initial.png <http://antares.in2p3.fr/GW/S200219ac_Initial.png>.
Considering the location probability provided by the LIGO/Virgo collaborations, there is a
55.5% chance that the GW emitter was in the ANTARES **upgoing** field of view at the time of
the alert.

No up-going muon neutrino candidate events were recorded in the ANTARES sky during a
+/-500s time-window centered on the time 2020-02-19 09:44:15 and in the 90% contour of the S200219ac
event. The expected number of atmospheric background events in the region visible by ANTARES is
3.87e-04 in the +/- 500s time window. An extended search during +/- 1 hour gives no
up-going muon neutrino coincidence. The expected number of atmospheric background events in the
region visible by ANTARES is 2.79e-03 in this larger time window.

ANTARES is the largest undersea neutrino detector, installed in the Mediterranean Sea, and it is
primarily sensitive to neutrinos in the TeV-PeV  energy range. At 10 TeV, the median angular
resolution for muon neutrinos is about 0.5 degrees. In the range 1-100 TeV ANTARES has a
competitive sensitivity to this position in the sky.