TITLE: GCN CIRCULAR NUMBER: 23611 SUBJECT: Search for counterpart to IceCube-190104A with ANTARES DATE: 19/01/05 15:22:49 GMT FROM: Damien Dornic at CPPM,France Alexis Coleiro (APC) and Damien Dornic (CPPM) report on behalf of the ANTARES Collaboration: Using data from the ANTARES detector, we have performed a follow-up analysis of the recently reported single high-energy starting event (HESE) neutrino IceCube-190104A (GCN 23605). The reconstructed origin was 39.1 degrees below the horizon for ANTARES. No up-going muon neutrino candidate events were recorded within three degrees of the IceCube event coordinates during a +/- 1h time-window centered on the IceCube event time. A search over an extended time window of +/- 1 day has also yielded no detection (65% visibility probability). This yields a preliminary 90% confidence level upper limit on the muon-neutrino fluence from a point source of 16 GeV.cm^-2 over the energy range 3.2 TeV - 3.5 PeV (the range corresponding to 5-95% of the detectable flux) for an E^-2 power-law spectrum, and 30 GeV.cm^-2 (620 GeV - 315 TeV) for an E^-2.5 spectrum. ANTARES is the largest neutrino detector installed in the Mediterranean Sea, and 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.