{
  "body": "The IceCube Collaboration (http://icecube.wisc.edu/) reports:\n\nIceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-Cascade 241019A (https://gcn.gsfc.nasa.gov/notices_amon_icecube_cascade/139992_18206409.amon) in a time range of 1000 seconds centered on the alert event time (2024-10-19 23:20:39.840 UTC to 2024-10-19 23:37:19.840 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, one track-like event is found within the 90% containment region of IceCube-Cascade 241019A. We find that this additional event is well described by atmospheric background expectations, with a p-value of 0.05 (which doesn’t account for statistical trials). 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 241019A ranges from 1.3e-01 to 7.4e+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 3e+02 GeV and 3e+06 GeV. \n\nA subsequent search was performed including 2 days of data centered on the alert event time (2024-10-18 23:28:59.840 UTC to 2024-10-20 23:28:59.840 UTC). In this search we report a p-value of 0.04, without accounting for statistical trials. This is 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 241019A ranges from 1.5e-01 to 7.5e+00 GeV cm^-2 in a 2 day time window. \n\nThe best-fit position for a potential source producing the cascade and the track-like events in the two-day search is RA: 171.4 deg, Dec: -16.6 deg (J2000), with an estimated error radius of 0.5 deg at 90% containment. There are three track-like events which include this best-fit position in their 90% error region, and are also inside of the 90% contour of the cascade event. Properties of these coincident events are shown below.\n\ndt [s]\t\tRA [deg]\tDec [deg]\tAngular uncertainty [deg] \n-----------------------------------------------------------------------------------------------------        \n415\t\t171.65\t\t-16.09\t\t1.18\n21967 \t\t170.90\t\t-16.81\t\t0.71\n62271\t\t171.44\t\t-16.72\t\t0.71\n\nwhere:\ndt = Time difference between the track-like event and the cascade event (i.e. T_track - T_cascade) [sec]\nAngular uncertainty = Angular uncertainty of track event: the radius of a circle representing 90% CL containment by area.\n\nThe 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.\n\n[1] IceCube Collaboration, R. Abbasi  et al., ApJ 910 4 (2021)\n",
  "submittedHow": "web",
  "format": "text/plain",
  "circularId": 37833,
  "submitter": "Jessie Thwaites at IceCube/U Wisc-Madison <thwaites@wisc.edu>",
  "createdOn": 1729545417661,
  "subject": "IceCube-Cascade 241019A: Upper limits from a search for additional neutrino events in IceCube",
  "bibcode": "2024GCN.37833....1I"
}