GCN Circular 26696

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

On 20/01/09 at 23:41:39.94 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 0.64 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/133609_37927131.amon <https://gcn.gsfc.nasa.gov/notices_amon_g_b/133609_37927131.amon>), more 
sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 20/01/09 
Time: 23:41:39.94 UT
RA: 164.49 (+4.94 -4.19 deg 90% PSF containment) J2000
Dec: 11.87 (+1.16 -1.36 deg 90% PSF containment) J2000

Due to the unique topology of this event, with a partially-contained track in the detector, it was challenging for online algorithms to reconstruct. The initially-reported direction was offset from this updated best-fit position by approximately 3 degrees.

We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino.

There is one Fermi 4FGL source within the 90% localization region, 4FGL J1103.0+1157    at RA: 165.77 deg, Dec: 11.97 deg (1.26 deg away from the best-fit event position). This source, which is associated with the quasar TXS 1100+122 at z=0.91, is also found in the 3FHL catalog.

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