TITLE: GCN CIRCULAR NUMBER: 41269 SUBJECT: IceCube-Cascade 250804A: Upper limits from a search for additional neutrino events in IceCube DATE: 25/08/07 16:04:49 GMT FROM: Alicia Mand at IceCube/UW-Madison aemand@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 250804A (https://gcn.nasa.gov/circulars/41235) in a time range of 1000 seconds centered on the alert event time (2025-08-04 07:50:12.960 UTC to 2025-08-04 08:06:52.960 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 250804A. We report a p-value of 1.00 in this time window. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-Cascade 250804A ranges from 1.4e-01 to 1.7e+01 GeV cm^-2 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 3e+02 GeV and 4e+06 GeV.

A subsequent search was performed, including 2 days of data centered on the alert event time (2025-08-03 07:58:32.960 UTC to 2025-08-05 07:58:32.960 UTC). In this case, we report a p-value of 0.43, consistent with no significant excess of track events. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-Cascade 250804A ranges from 1.6e-01 to 1.7e+01 GeV cm^-2 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)

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