TITLE:   GCN CIRCULAR
NUMBER:  33732
SUBJECT: IceCube-230506A: IceCube observation of a high-energy neutrino candidate
DATE:    23/05/06 18:20:35 GMT
FROM:    Erik Blaufuss at University of Maryland, College Park <blaufuss@umd.edu>

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

On 2023-05-06 at 15:53:45.93 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 0.76 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/137910_29871391.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2023-05-06
Time:  15:53:45.93 UT
RA: 50.19 (+4.05 / -2.97 deg 90% PSF containment) J2000
Dec: +21.06 (+3.33 /  -2.13 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.

Several gamma-ray sources listed in the 4FGL-DR3 Fermi-LAT catalog are located within the 90% containment radius of the event. The nearest source is 4FGL J0318.7 +2135 located at RA 49.69 deg, Dec +21.60 deg J2000, 0.71 deg away 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