GCN Circular 23338

The IceCube Collaboration (http://icecube.wisc.edu/) reports:

On October 14, 2018, 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) track selection. The IceCube detector was in a normal operating state. HESE tracks have a neutrino interaction vertex inside the detector and produce a muon that only partially traverses the detector volume, and have a high light level (a proxy for energy). An inspection of the event does not reveal any feature to rule out this event as an astrophysical candidate. However, this event has a light level that is right above the analysis threshold so there is a non-negligible probability that this event is an atmospheric background.

After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon/12296708_131624.amon), more 
sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2018/10/14 
Time: 11:52:46 UT
RA: 225.15 [-2.85,+1.40] (deg  90% PSF containment) J2000
Dec: -34.80 [-1.85,+1.15] (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