TITLE: GCN CIRCULAR NUMBER: 26435 SUBJECT: IceCube-191215A - IceCube observation of a high-energy neutrino candidate event DATE: 19/12/15 13:56:46 GMT FROM: Robert Stein at DESY The IceCube Collaboration (http://icecube.wisc.edu/ ) reports: On 19/12/15 at 11:09:57.63 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 0.34 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/133433_29047901.amon ), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 19/12/15 Time: 11:09:57.63 UT RA: 285.87 (+2.88 -3.19 deg 90% PSF containment) J2000 Dec: 58.92 (+1.85 -2.25 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 are no Fermi 4FGL or 3FHL catalog sources in the 90% uncertainty region. The nearest gamma-ray source in either catalog is 4FGL J1858.7+5708 at RA: 284.70 deg, Dec: 57.15 deg (1.88 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