GCN Circular 22105

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

On November 6, 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 Extremely High Energy (EHE) track event 
selection. The IceCube detector was in a normal operating state. EHE 
events typically have a neutrino interaction vertex that is outside the 
detector and 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/17569642_130214.amon), more 
sophisticated reconstruction algorithms have been applied offline, with 
the direction refined to:

Date: 17/11/06 (yy/mm/dd)
Time: 18:39:39.21 UT
RA: 340.00 (-0.50/+0.70 deg 90% PSF containment) J2000
Dec: +7.40 (-0.25/+0.35 deg 90% PSF containment) J2000

Initial offline analysis of this event indicates that the event is 
consistent with being produced by a neutrino with energy in excess of 1 
PeV. The initially reported signalness and energy values are likely 
underestimated.

As indicated in the initial notice, the neutrino candidate is temporally 
close to Fermi GBM trigger 531686417. However, recently, Fermi GBM has 
been triggering frequently on a galactic source that is not spatially 
coincident with the event reported here.

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