TITLE: GCN CIRCULAR NUMBER: 22016 SUBJECT: IceCube-171015A - IceCube observation of a high-energy neutrino candidate event DATE: 17/10/15 14:30:35 GMT FROM: Erik Blaufuss at U. Maryland/IceCube The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 15 October, 2017 IceCube detected a track-like, very-high-energy event with a high probability of being of astrophysical origin. The event was identified by the High Energy Starting Event (HESE) selection. The IceCube detector was in a normal operating state. HESE events have a neutrino vertex inside of the detector (to reduce background) and have a high light level (a proxy for energy). After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon/56068624_130126.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 2017-10-15 Time: 01:34:30.06 UT RA: 162.86 deg (-1.70 deg / +2.60 deg 90% PSF containment) J2000 Dec: -15.44 deg (-2.00 deg / +1.60 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. 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