TITLE: GCN CIRCULAR NUMBER: 42369 SUBJECT: IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube DATE: 25/10/19 18:45:31 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-251018A (https://gcn.nasa.gov/circulars/42352) in a time range of 1000 seconds centered on the alert event time (2025-10-18 04:57:22.970 UTC to 2025-10-18 05:14:02.970 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-251018A. 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, is 1.5e-01 GeV cm^-2 within the 90% spatial containment region of IceCube-251018A 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 6e+04 GeV.
A subsequent search was performed including 2 days of data centered on the alert event time (2025-10-17 05:05:42.970 UTC to 2025-10-19 05:05:42.970 UTC). In this case, we report a p-value of 0.02, 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 1.7e-01 to 1.8e-01 GeV cm^-2 within the 90% spatial containment region of IceCube-251018A 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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