GCN Circular 20247

Erik Blaufuss(University of Maryland) reports on behalf of the IceCube Collaboration (http://icecube.wisc.edu/).

On 2016/12/10 IceCube detected a track-like, very-high-energy event with a high probability of being of astrophysical origin. The event was a Extremely High Energy (EHE) event. The IceCube detector was in a normal operating state. EHE events have a neutrino interaction vertex outside the detector, produce a muon that traverses the detector volume and have a high light level (a proxy for energy).

After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon/80127519_128906.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2016/12/10
Time: 16 20:07:16  UT
RA: 46.58 deg (+1.10 -1.00deg 90% PSF containment) J2000
Dec: 14.98 deg (+0.45 -0.40 deg 90% PSF containment) J2000

Additionally, we confirm the astrophysical signal probability reported initially.  This event was found at the threshold for alert generation, with roughly equal chances of being of astrophysical origin or arising from an atmospheric (background) neutrino interaction.  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