TITLE: GCN CIRCULAR NUMBER: 45009 SUBJECT: IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube DATE: 26/06/19 16:38:39 GMT FROM: Yuhua Yao at IceCube/UW-Madison <yyao255@icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-Cascade 260618A (https://gcn.gsfc.nasa.gov/notices_amon_icecube_cascade/142737_24549075.amon) in a time range of 1000 seconds centered on the alert event time (2026-06-18 05:19:19.175 UTC to 2026-06-18 05:35:59.175 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-Cascade 260618A. We report a p-value of 1.00 in this time window. IceCube’s sensitivity to neutrino point sources with an E^-2.5 spectrum, expressed as E^2 dN/dE evaluated at 1 TeV, ranges from 1.4e-01 to 1.5e-01 GeV cm^-2 within the 90% spatial containment region of IceCube-Cascade 260618A in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 2e+02 GeV and 8e+04 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2026-06-17 05:27:39.175 UTC to 2026-06-19 05:27:39.175 UTC). In this case, we report a p-value of 0.48, consistent with no significant excess of track events. IceCube’s sensitivity to neutrino point sources with an E^-2.5 spectrum, expressed as E^2 dN/dE evaluated at 1 TeV, ranges from 1.6e-01 to 1.8e-01 GeV cm^-2 within the 90% spatial containment region of IceCube-Cascade 260618A in a 2 day time window. 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. [1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021) View this GCN Circular online at https://gcn.nasa.gov/circulars/45009. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...