TITLE: GCN CIRCULAR NUMBER: 36261 SUBJECT: IceCube-240419A: Upper limits from a search for additional neutrino events in IceCube DATE: 24/04/23 18:50:37 GMT FROM: Sam Hori at IceCube/U Wisc-Madison sahori@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-240419A (https://gcn.nasa.gov/circulars/36195 ) in a time range of 1000 seconds centered on the alert event time (2024-04-19 23:17:21.040 UTC to 2024-04-19 23:34:01.040 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-240419A. 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-240419A ranges from 1.4e-01 to 1.5e-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 2e+05 GeV.

A subsequent search was performed including 2 days of data centered on the alert event time (2024-04-18 23:25:41.040 UTC to 2024-04-20 23:25:41.040 UTC). In this case, we report a p-value of 0.34, 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-240419A is 1.6e-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.edumailto:roc@icecube.wisc.edu.

[1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021)

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