GCN Circular 21479
M. Ageron (CPPM/CNRS), B. Baret (APC/CNRS), A. Coleiro (IFIC & APC), 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 G297595 event using the initial LIGO/Virgo Bayestar probability map at event time. The ANTARES visibility at the time of the alert together with the 90% contour of the probability map are shown in: https://www.cppm.in2p3.fr/~dornic/events/G297595/skymap_140817.png <https://www.cppm.in2p3.fr/~dornic/events/G297595/skymap_140817.png> (gwantares/GW@ANT30). Considering the location probability provided by the LIGO collaboration, there is a 98% chance that the GW emitter was in the ANTARES field of view. No up-going muon neutrino candidate events were recorded within the 90% contour during a +/- 500s time-window centered on the G297595 event time. The expected number of atmospheric background events in the region visible by ANTARES is ~1.2e-2 in the +/- 500s time window. An extended search during +/- 1 hour gives no up-going neutrino coincidence. An estimate of the upper limit on the associated neutrino fluence will be sent in a subsequent circular. ANTARES, being installed in the Mediterranean Deep Sea, is the largest neutrino detector in the Northern Hemisphere. It is primarily sensitive to astrophysical neutrinos in the TeV-PeV energy range. At 10 TeV, the median angular resolution for muon neutrinos is below 0.5 degrees. In the range 1-100 TeV, ANTARES has the best sensitivity to a large fraction of the Southern sky.