GCN Circular 26391
Alexis Coleiro (APC/Univ 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 HAWC alert (https://gcn.gsfc.nasa.gov/notices_amon_hawc/9066_1171.amon <https://gcn.gsfc.nasa.gov/notices_amon_hawc/9066_1171.amon>). No up-going muon neutrino candidate events were detected within 3 degrees from the event coordinates over a time window of +/-1h during which the potential source remained visible in the up-going field of view of ANTARES. A search over an extended time window of +/-1 day has also yielded no detection (50.5% visibility). This leads to a preliminary 90% confidence level upper limit on the muon-neutrino radiant fluence from a point source of about 17 GeV.cm^-2 over the energy range 3 TeV - 3 PeV (the range corresponding to 5-95% of the detectable flux) for an E^-2 power-law spectrum, and about 69 GeV.cm^-2 (600 GeV - 3 TeV) for an E^-2.5 spectrum, computed for the time of the alert. ANTARES 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.