TITLE: GCN CIRCULAR NUMBER: 25408 SUBJECT: Fermi GBM-190816+LIGO/Virgo : no neutrino counterpart candidate in ANTARES search DATE: 19/08/20 13:03:18 GMT FROM: Damien Dornic at CPPM,France 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 Fermi GBM-190816+LIGO/Virgo subthreshold GW trigger event using the 90% contour of the joint probability map provided by Fermi-GBM + LSC-Virgo (GCN#25406 ). 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/2019-08-16_GBM-190816-w.png . Considering the location probability provided by the Fermi-GBM and LIGO/Virgo, there is a 37% 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 2019-08-16 21:22:13 and in the 90% contour of the GBM-190816+LIGO/Virgo event. The expected number of atmospheric background events in the region visible by ANTARES is 3.1e-03 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 2.2e-02 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.