GCN Circular 31111

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 HAWC-211123A alert (event 110400_42 <https://gcn.gsfc.nasa.gov/notices_amon_hawc/110400_42.amon>). 

No up-going muon neutrino candidate events were detected within the error box of the HAWC event during a +/- 1h time-window centered on the HAWC event time (T0), and over which the potential source remained visible 88% of time in the up-going field of view of ANTARES. At T0, the elevation of the alert was -7.3 degrees below the horizon for ANTARES. 

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 70 GeV.cm^-2 (0.5 - 280 TeV) for an E^-2.5 spectrum. 
A search over an extended time window of +/-1 day has also yielded no detection (54% visibility). 

ANTARES <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.