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GCN Circular 25120

LIGO/Virgo S190720a : no neutrino counterpart candidate in ANTARES search
2019-07-20T10:12:24Z (5 years ago)
Antoine Kouchner at ANTARES Collaboration <>
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 S190720a event using the 90% contour of the bayestar probability
map provided by the GW interferometers (GCN#25115 <>). The ANTARES visibility at the time of the
alert, together with the 50% and 90% contours of the probability map are shown at <>.
Considering the location probability provided by the LIGO/Virgo collaborations, there is a
41.6% 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 2019-07-20 00:08:36 and in the 90% contour of the S190720a event.
The expected number of atmospheric background events in the region visible by ANTARES is 3.50e-04 in the +/- 500s time window.
An extended search during +/- 1 hour gives no upgoing muon neutrino candidate in coincidence with the 90% contour.
In this extended time window, an event (Time = 01:06:24, RA=200.3deg, Dec=7.6 deg) is seen outside the 99% contour, close to the ANTARES horizon.
Considering the expected number of atmospheric background events in the ANTARES upgoing field of view, this had a ~10% chance to occur.

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.
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