TITLE: GCN CIRCULAR NUMBER: 37625 SUBJECT: IceCube-240929A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 24/09/29 14:52:14 GMT FROM: Erik Blaufuss at University of Maryland, College Park <blaufuss@umd.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 2024-09-29 at 09:55:54.03 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 0.7553 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/139912_46959751.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 2024-06-29 Time: 09:55:54.03 UT RA: 180.66 (+0.57, -0.71 deg 90% PSF containment) J2000 Dec: 18.92 (+0.55, -0.54 deg 90% PSF containment) J2000 No Fermi 4FGL or 3FHL catalog source are in the 90% uncertainty region. However, given the promising characteristics of the candidate neutrino event, we encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source associated with it. 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 View this GCN Circular online at https://gcn.nasa.gov/circulars/37625. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...