GCN Circular 26623
Alexis Coleiro (APC/Universite de Paris) and Damien Dornic (CPPM/CNRS) on behalf of the ANTARES Collaboration. <br> Using data from the ANTARES detector, we have performed a follow-up analysis of the recently reported single track-like event IceCube-191231A (GCN 26620 <https://gcn.gsfc.nasa.gov/gcn3/26620.gcn3>). The original reconstructed origin was 17 degrees below the horizon for ANTARES. <br> No up-going muon neutrino candidate events were recorded at the location of the IceCube event coordinates (accounting for the reported uncertainties) during a +/- 1h time-window centered on the IceCube event time, and over which the potential source remained visible all time. A search over an extended time window of +/- 1 day has also yielded no detection (40% visibility). <br> This leads to a preliminary 90% confidence level upper limit on the muon-neutrino fluence from a point source of 15 GeV.cm^-2 over the energy range 5.3 TeV - 5.0 PeV (the range corresponding to 5-95% of the detectable flux) for an E^-2 power-law spectrum, and 32 GeV.cm^-2 (960 GeV - 470 TeV) for an E^-2.5 spectrum. <br> ANTARES <http://antares.in2p3.fr/ <http://antares.in2p3.fr/>> is the largest undersea neutrino detector (Mediterranean Sea) and it is primarily sensitive to astrophysical 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.