TITLE: GCN CIRCULAR NUMBER: 39203 SUBJECT: IceCube-250207A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 25/02/07 13:48:55 GMT FROM: Giacomo Sommani at Ruhr-Universität Bochum gsommani@icecube.wisc.edu

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

On 2025-02-07 at 02:07:55.27 UT IceCube detected a track-like event with a high 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 1.45 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/140472_78196104.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2025-02-07 Time: 02:07:55.27 UT RA: 132.93 (+2.05, -1.89 deg 90% PSF containment) J2000 Dec: 20.66 (+1.28, -1.40 deg 90% PSF containment) J2000

Two Fermi 4FGL or 3FHL catalog sources are in the 90% uncertainty region: 4FGL J0854.8+2006 and 4FGL J0856.8+2056, located 0.9 deg and 1.2 deg away from the best-fit position, respectively. 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

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