TITLE:   GCN CIRCULAR
NUMBER:  40103
SUBJECT: IceCube-250406A - IceCube observation of a high-energy neutrino candidate track-like event
DATE:    25/04/07 08:06:32 GMT
FROM:    A. Zegarelli at Ruhr University Bochum <azegarelli@icecube.wisc.edu>

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

On 2025-04-06 at 22:50:35.34 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 bronze alerts is 50%. This alert has an estimated false alarm rate of 0.9358 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/140752_31006975.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2025-04-06
Time:   22:50:35.34 UT
RA: 81.47 (+0.54, -0.53 deg 90% PSF containment) J2000
Dec: 16.96 (+0.42, -0.50 deg 90% PSF containment) J2000

No gamma-ray sources from 4FGL or 3FHL catalogs are in the 90% uncertainty region. We encourage further follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino.

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