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GCN Circular 31198

AMON NuEm-211020A: No neutrino counterpart detected with ANTARES
2021-12-10T13:27:55Z (2 years ago)
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 NuEm-211209A alert (GCN #31192 <>). 

No up-going muon neutrino candidate events were detected within 3 degrees from the coincidence coordinates over a time period [12/09/2021 00h50 - 04h39 UTC] corresponding to 75% 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 of about 15^-2 over the energy range 3 TeV ��� 3.3 PeV (the range corresponding to 5-95% of the detectable flux) for an E^-2 power-law spectrum, and about 26^-2 (0.5 - 290 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 (53% visibility). 

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.
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