TITLE:   GCN CIRCULAR
NUMBER:  40369
SUBJECT: IceCube-250506A - IceCube observation of a high-energy neutrino candidate track-like event
DATE:    25/05/06 18:12:57 GMT
FROM:    A. Zegarelli at Ruhr University Bochum <azegarelli@icecube.wisc.edu>

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

On 25-05-06 at 14:14:12.09 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 0.9761 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/140896_73492707.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 25-05-06
Time: 14:14:12.09 UT
RA: 116.50 (+0.59/-0.57 deg 90% PSF containment) J2000
Dec: 35.32 (+0.48/-0.43 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.

No known gamma-ray sources listed in the Fermi 4FGL-DR4 or 3FHL catalogs are located within the 90% uncertainty region of the event.

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