GCN Circular 28415
Alexis Coleiro (APC/Universite de Paris) and Damien Dornic (CPPM/CNRS) on behalf of the ANTARES Collaboration. Using data from the ANTARES detector, we have performed a follow-up analysis of the recently reported single track-like event IceCube-200911A (GCN 28411 <https://gcn.gsfc.nasa.gov/gcn3/28411.gcn3 <https://gcn.gsfc.nasa.gov/gcn3/28411.gcn3>>). The reconstructed origin was 7.3 degrees below the horizon for ANTARES. No up-going muon neutrino candidate events were recorded within the 90% error box of the IceCube event during a +/- 1h time-window centered on the IceCube event time, and over which the potential source remained visible all time. This leads to a preliminary 90% confidence level upper limit on the muon-neutrino fluence from a point source of 14 GeV.cm^-2 over the energy range 10 TeV - 8 PeV (the range corresponding to 5-95% of the detectable flux) for an E^-2 power-law spectrum, and 34 GeV.cm^-2 (1.5 TeV - 740 TeV) for an E^-2.5 spectrum. A search over an extended time window of +/- 1 day has also yielded no detection (23.5% visibility). 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.