TITLE: GCN CIRCULAR NUMBER: 32475 SUBJECT: IceCube-220822A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 22/08/22 23:07:55 GMT FROM: Dr. Massimiliano Lincetto at Ruhr-Universitaet Bochum lincetto@astro.rub.de

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

On 2022-08-22 20:26:30.03 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 2.005 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/136973_28816141.amon) more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2022-08-22 Time: 20:26:30.03 UT RA: 273.08 (+2.47, -2.50 deg 90% PSF containment) J2000 Dec: +21.54 (+0.94, -1.18 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.

Two gamma-ray sources listed in the 4FGL Fermi-LAT catalog are located in the 90% containment region. The sources are 4FGL J1809.3+2042 and 4FGL J1819.1+2133 (3FHL J1819.2+2135), respectively located at 1.08 and 1.58 deg from the best fit position.

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