GCN Circular 25913

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

On 19/10/01 at 20:09:18.17 UT IceCube detected a track-like event with a high probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_Gold alert stream.  The average astrophysical neutrino purity for Gold alerts is 50%. This alert has an estimated false alarm rate of 0.86 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection.

After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/133119_22683750.amon <https://gcn.gsfc.nasa.gov/notices_amon_g_b/133119_22683750.amon>), more 
sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 19/10/01
Time: 20:09:18.17 UT
RA: 314.08 (+6.56 -2.26 deg 90% PSF containment) J2000
Dec: 12.94 (+1.50 -1.47 deg 90% PSF containment) J2000

Given that the track is partially obscured by a natural dust layer in the ice, the 90% uncertainty region reported by the reconstruction algorithms is larger than average error contours. 

There are two Fermi 4FGL catalogue sources within the 90% contour. The nearest is 4FGL J2052.7+1218, located 1.1 degrees away at the edge of the 50% localization region. One additional source, 4FGL J2115.2+1218, is also located within the 90% contour at a distance of 4.8 degrees from the best fit.

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