TITLE: GCN CIRCULAR NUMBER: 31476 SUBJECT: AMON IC_HAWC NuEm-220116A: No neutrino counterpart detected with ANTARES DATE: 22/01/18 07:51:06 GMT FROM: Antoine Kouchner at ANTARES Collaboration 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 AMON IC-HAWC coincidence alert NuEm-220116A (https://gcn.gsfc.nasa.gov/notices_amon_nu_em/0_105322.amon). No up-going muon neutrino candidate events were detected within 3 degrees from the coincidence coordinate over a time period [21h13 - 23h26 UT] corresponding to 34.5% of the HAWC transit time mentioned in the AMON notice, and during which the potential source remained visible in the up-going field of view of ANTARES. This leads to a preliminary 90% confidence level upper limit on the muon neutrino radiant fluence from a point source located at the coordinates of the coincidence as reported by AMON, of about 14 GeV.cm^-2 over the energy range 6 TeV - 6 PeV (the range corresponding to 5-95% of the detectable flux) for an E^-2 power-law spectrum, and about 31 GeV.cm^-2 (1 - 580 TeV) for an E^-2.5 spectrum. These indicative limits have been computed for the end of the HAWC transit time. A search over an extended time window of +/-1 day has also yielded no detection (34% visibility). ANTARES (https://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.