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GCN Circular 31225

IceCube-211208A: No neutrino counterpart detected with ANTARES
2021-12-13T08:38:46Z (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 bronze track event IceCube-211208A (GCN#31191 <>). The reconstructed origin was about 10 degrees above the horizon for ANTARES at the time of the alert.

Extending slightly the analysis to include the events just above the horizon, no muon neutrino candidate events were recorded within the 90% error box of the IceCube event during a +/- 1h time-window centered on the IceCube event time.

A search over an extended time window of +/- 1 day also yielded no detection (41% visibility). Over this time period, and restricting the search to the periods when the source remained below the horizon, this leads to a preliminary 90% confidence level upper limit on the muon-neutrino radiant fluence from a point source of about 17^-2 over the energy range 5 TeV ��� 5 PeV (the range corresponding to 5-95% of the detectable flux) for an E^-2 power-law spectrum, and 43^-2 (1 - 500 TeV) for an E^-2.5 spectrum. 

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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