GCN Circular 19787

D.F. Cowen reports on behalf of the IceCube Collaboration:

IceCube detected a candidate cosmic neutrino IceCube-160806A, "AMON 
ICECUBE EHE 128311 26552458" at 12:21:33.00 UT on 16/08/06 
(http://gcn.gsfc.nasa.gov/notices_amon/26552458_128311.amon) The event 
was an Extremely High Energy (EHE) event with track-like characteristics 
and it arrived when the IceCube detector was in a normal operating 
state.  EHE events satisfy a combination of high light level and zenith 
angle that enhances astrophysical signal relative to cosmic-ray-induced 
backgrounds.  In contrast to the other active IceCube high energy 
track-like neutrino alert stream, known as "HESE," EHE events are not 
required to start within the IceCube detector fiducial volume.

After the initial automated alert, more sophisticated reconstruction
algorithms have been applied offline, with the direction refined to
RA=122.81d and DEC=-0.8061d (J2000) in revision 1 of this alert.  The 
position uncertainty is estimated from the initial realtime 
reconstruction from revision 0 of this alert, at 0.1 degrees or 6.7 
arcminutes radius (stat. only, 50% containment).  Lacking inclusion of 
systematic effects, we expect this uncertainty underestimates the true 
uncertainty by roughly a factor of five.  We encourage followup 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