Subject: IceCube-250905A – IceCube observation of a high-energy neutrino candidate track-like event
Event: IceCube-250905A
Date: 2025-09-05T22:22:56Z
From: Erik Blaufuss at University of Maryland, College Park <blaufuss@umd.edu>
The IceCube Collaboration (http://icecube.wisc.edu/) reports:
On 2025-09-05 20:08:36.01 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 0.41 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/141315_25569816.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:
Date: 2025-09-05
Time: 20:08:36.01 UT
RA: 348.31 (+0.93, -1.09 deg 90% PSF containment) J2000
Dec: 38.87 (+0.78, -0.86 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
