TITLE: GCN CIRCULAR NUMBER: 30468 SUBJECT: IceCube-210717A: IceCube observation of a high-energy neutrino candidate track-like event DATE: 21/07/18 15:22:53 GMT FROM: Cristina Lagunas Gualda at DESY The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 21/07/17 at 15:45:19.48 UT IceCube detected a high-energy starting event [1]. The IceCube online selection did not identify this event as a Gold or Bronze starting track. However, based on advanced reconstructions performed offline, we identify this event as a potential astrophysical neutrino of interest to the community, given its topology and light deposition. Because the event was not identified as either Gold or Bronze, we do not currently report a false alert rate or signalness. The IceCube detector was in a normal operating state at the time of detection. Advanced reconstruction algorithms have been applied offline, with the direction estimated to be: Date: 21/07/17 Time: 15:45:19.48 UT RA: 46.49 (+ 2.40 - 2.57 deg 90% PSF containment) J2000 Dec: -1.34 (+ 2.63 - 3.41 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 J0304.5-0054, located at RA 46.14 deg and Dec -0.91 deg (J2000), at a distance of 0.55 degrees from the best-fit location. The source is also listed in the Fermi 3FHL hard-spectrum source catalog. 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 [1] The IceCube Collaboration, Phys. Rev. Lett. 113, 101101 (2014)