TITLE: GCN CIRCULAR NUMBER: 20119 SUBJECT: IceCube-161103: IceCube observation of a very-high-energy neutrino DATE: 16/11/03 14:40:56 GMT FROM: Ignacio Taboada at Georgia Inst of Tech Ignacio Taboada (Georgia Institute of Technology) reports on behalf of the IceCube Collaboration (http://icecube.wisc.edu/). On 2016/11/03 IceCube detected a track-like very-high-energy event with a high probability of being of astrophysical origin. The event was a High Energy Starting Event (HESE). 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 (http://gcn.gsfc.nasa.gov/notices_amon/38561326_128672.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 2016/11/03 Time: 09:07:31.12 UT RA: 40.83 deg (+1.10 -0.70 deg 90% PSF containment) J2000 Dec: 12.56 deg (+1.10 -0.65 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