TITLE: GCN CIRCULAR NUMBER: 26922 SUBJECT: Fermi-LAT ANTARES coincidence: IceCube neutrino search DATE: 20/01/28 22:37:33 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 direction of the Fermi-LAT-ANTARES coincidence (https://gcn.gsfc.nasa.gov/gcn3/26915.gcn3) in a centered two-day time window (2020-01-26 18:52:02.95 UTC to 2020-01-28 18:52:02.95 UTC), during which IceCube was collecting good quality data. The time window of the search contains GW event S200128d (https://gcn.gsfc.nasa.gov/gcn3/26906.gcn3), that follows approximately 7.5 hours later and is spatially coincident (50% credible region). Zero track-like events are found in spatial coincidence with the Fermi-LAT-ANTARES coincidence during this time period. We accordingly derive a time-integrated muon-neutrino flux upper limit at the reported location of E^2 dN/ dE = 9.32 x 10^-4 TeV cm^-2 at 90% CL, under the assumption of an E^-2 power law. The southern declination of this coincidence suppresses IceCube’s sensitivity to TeV neutrinos, and 90% of events IceCube would detect from a source at this declination with an E^-2 spectrum are approximately between 100 TeV and 40 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.