GCN Circular 31144

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 211128A (https://gcn.gsfc.nasa.gov/notices_amon_icecube_cascade/135946_6354173.amon) in a time range of 1000 seconds centered on the alert event time (2021-11-28 02:34:47.790 UTC to  2021-11-28 02:51:27.790 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 211128A. 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 211128A ranges from 1.3e-01 to 3.1e+00 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 1e+04 GeV and 2e+06 GeV.

A subsequent search was performed including 2 days of data centered on the alert event time (2021-11-27 02:43:07.790 UTC to 2021-11-29 02:43:07.790 UTC). In this case, we report a p-value of 0.32, 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 211128A ranges from 1.5e-01 to 3.0e+00 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<mailto:roc@icecube.wisc.edu>.

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