GCN Circular 20929

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

On 21 March, 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, 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/80305071_129307.amon), more 
sophisticated reconstruction algorithms have been applied offline, with 
the direction refined to:

Date: 2017-03-21
Time: 07:32:20.69 UT
RA: 98.30  (+/- 1.2  deg  90% PSF containment) J2000
Dec:  -15.02(+/- 1.2 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.

This event was found to be close to  the edge of the instrumented 
detector volume, which has
increased the overall direction uncertainty for this event.

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