TITLE: GCN CIRCULAR NUMBER: 43151 SUBJECT: IceCube-251218A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 25/12/18 21:55:53 GMT FROM: A. Zegarelli at Ruhr University Bochum <azegarelli@icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 25-12-18 at 20:21:00.63 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_BRONZE alert stream. The average astrophysical neutrino purity for Bronze alerts is 30%. This alert has an estimated false alarm rate of 0.8234 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection. After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/141741_9008919.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 25-12-18 Time: 20:21:00.63 UT RA: 353.60 (+0.90/-0.74 deg 90% PSF containment) J2000 Dec: 44.15 (+0.46/-0.45 deg 90% PSF containment) J2000 We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino. There is one Fermi 4FGL-DR4 source in the 90% uncertainty region, i.e., the unassociated gamma-ray source 4FGL J2331.6+4430 at RA: 552.90 deg, Dec: 44.51 deg J2000 (0.62 deg away from the best-fit event position). 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 View this GCN Circular online at https://gcn.nasa.gov/circulars/43151. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...