TITLE: GCN CIRCULAR NUMBER: 34166 SUBJECT: IceCube-230707B - IceCube observation of a high-energy neutrino candidate track-like event DATE: 23/07/07 19:37:40 GMT FROM: Marcos Santander at U of Alabama The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 23-07-07 at 18:56:51.44 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 1.358 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/138125_29513102.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 23-07-07 Time: 18:56:51.44 UT RA: 127.18 (+11.41 deg, -8.66 deg 90% PSF containment) J2000 Dec: 20.74 (+11.41 deg, -9.16 deg 90% PSF containment) J2000 The large directional uncertainty is due to the muon that triggered the event clipping a corner of the detector and therefore producing a short track. We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino. Given the size of the uncertainty region, there is a large number (>30) of Fermi 4FGL-DR3 or 3FHL catalog sources in the 90% uncertainty region. 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