TITLE: GCN CIRCULAR NUMBER: 29454 SUBJECT: IceCube-210210A: IceCube observation of a high-energy neutrino candidate event DATE: 21/02/10 14:42:58 GMT FROM: Cristina Lagunas Gualda at DESY The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 21/02/10 at 11:53:55.65 UT IceCube detected a track-like event with a high probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_GOLD alert stream. The average astrophysical neutrino purity for Gold alerts is 50%. This alert has an estimated false alarm rate of 0.464 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/134979_17138286.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 21/02/10 Time: 11:53:55.65 UT RA: 206.06 (+ 1.40 - 0.95 deg 90% PSF containment) J2000 Dec: 4.78 (+ 0.62 - 0.56 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-LAT 4FGL source inside the 90% localization region, 4FGL J1342.7+0505, located at RA 205.69 deg and Dec 5.09 deg (J2000), at a distance of 0.49 degrees from the best-fit location. 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