TITLE: GCN CIRCULAR NUMBER: 24039 SUBJECT: Search for additional neutrino events from the direction of IceCube-190331A with IceCube DATE: 19/04/01 16:26:27 GMT FROM: Alex Pizzuto at ICECUBE/U of Wisconsin The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search for additional track-like muon neutrino events arriving from the direction of IceCube-190331A (https://gcn.gsfc.nasa.gov/gcn3/24028.gcn3) in a time range of 2 days centered on the alert event time (2019-03-30 06:55:43.44 UTC to 2019-04-01 06:55:43.44 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero additional track-like events are found in spatial coincidence with the 90% PSF containment of IceCube-190331A. We find that these data are well described by atmospheric background expectations, with a p-value of 1.0. Accordingly, these data would represent a time-integrated muon-neutrino flux upper limit assuming an E^-2 spectrum (E^2 dN/dE) at the 90% CL of 3.0 x 10^-4 TeV cm^-2 for this observation period. 90% of events IceCube would detect from a source at this declination with an E^-2 spectrum are between approximately 10 TeV and 1 PeV. A subsequent search was performed to include the previous month of data (2019-03-01 06:55:43.44 UTC to 2019-04-01 06:55:43.44 UTC). In this case, we also report a p-value of 1.0, consistent with no significant excess of track events, and a corresponding time-integrated muon-neutrino flux upper limit assuming an E^-2 spectrum (E^2 dN/dE) at the 90% CL of 3.8 x 10^-4 TeV cm^-2. 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