GCN Circular 24387

M. Ageron (CPPM/CNRS), B. Baret (APC/CNRS), A. Coleiro (APC/Universite Paris Diderot), M. Colomer (APC/Universite Paris Diderot)), D. Dornic (CPPM/CNRS), A. Kouchner (APC/Universite Paris Diderot), 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 S190503bf event using the 90% contour of the probability map provided by the GW interferometers at event time. The ANTARES visibility at the time of the alert, together with the 50% and 90% contours of the probability map (initial bayestar map) are shown in https://www.cppm.in2p3.fr/~dornic/events_runo3/S190503bf.png. Considering the location probability provided by the LIGO/Virgo collaborations, there is a 98% 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 (2019-05-03 18:54:04 UT) and in the 90% contour of the S190503bf event. The expected number of atmospheric background events in the region visible by ANTARES is 2.2e-4 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 1.6e-3 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.