TITLE:   GCN CIRCULAR
NUMBER:  39549
SUBJECT: IceCube-250302A - IceCube observation of a high-energy neutrino candidate track-like event
DATE:    25/03/02 16:04:00 GMT
FROM:    A. Zegarelli at Ruhr University Bochum <azegarelli@icecube.wisc.edu>

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

On 2025-03-02 at 03:20:52.90 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 0.1579 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/140601_60511904.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2025-03-02
Time:  03:20:52.90 UT
RA: 348.05 (+0.38 -0.43 deg  90% PSF containment) J2000
Dec: 3.77 (+0.42 -0.41 deg 90% PSF containment) J2000

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

However, given the particularly high signalness (~97%) and energy (~1.5 PeV) of this event, we strongly encourage 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