TITLE: GCN CIRCULAR NUMBER: 31516 SUBJECT: Fermi-LAT-ANTARES 220121a: upper limits from a search for coincident neutrinos with IceCube DATE: 22/01/21 21:07:12 GMT FROM: Alex Pizzuto at ICECUBE/U of Wisconsin The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search for track-like muon neutrino events arriving from the best-fit localization region of the recent coincidence between one ANTARES neutrino and one Fermi LAT photon (https://gcn.gsfc.nasa.gov/gcn3/31514.gcn3). The search was performed using a time window one day in duration centered on the alert time (2022-01-20 13:02:01 UTC to 2022-01-21 13:02:01 UTC), during which IceCube was collecting good quality data. We find that the data are consistent with atmospheric background expectations, with a p-value of 1. We accordingly derive a time-integrated muon-neutrino flux upper limit for this source of E^2 dN/ dE = 9.3 x 10^-4 TeV cm^-2 at 90% CL, under the assumption of an E^-2 power law. 90% of events IceCube would detect from a source at this declination with an E^-2 spectrum have energies in the approximate energy range between 100 TeV and 20 PeV. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.edu.