GCN Circular 35328

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

On 2023-12-11 at 00:47:31.79 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_Bronze alert stream. The average astrophysical neutrino purity 
for Bronze alerts is 30%. This alert has an estimated false alarm rate of 3.30 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/138669_4054005.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2023-12-11
Time: 00:47:31.79 UT
RA: 311.48 (+1.15, -2.33 deg  90% PSF containment) J2000
Dec: +10.28 (+0.67, -0.68 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.

Three gamma-ray sources listed in the 4FGL-DR4 Fermi-LAT catalog are located in the 90% uncertainty of the event. The sources are 4FGL J2044.0+1036, 4FGL J2047.3+1051 and 4FGL J2049.9+1002. The three objects are located 0.6, 0.7 and 1.0 deg away from the best-fit position, respectively. 4FGL J2049.9+1002 was observed in a high-emission state between September and November of this year by Fermi LAT: https://fermi.gsfc.nasa.gov/ssc/data/access/lat/LightCurveRepository/source.html?source_name=4FGL_J2049.9+1002. 
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