TITLE: GCN CIRCULAR NUMBER: 24910 SUBJECT: IceCube-190629A - IceCube observation of a high-energy neutrino candidate event DATE: 19/06/29 22:47:28 GMT FROM: Erik Blaufuss at U. Maryland/IceCube The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 29/06/19 at 19:24:15.12 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 0.64 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/132768_5390846.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 29/06/19 Time: 19:24:15.12 UT RA: 27.22 (Dec value too close to pole for accurate error on RA) J2000 Dec: 84.33 (+4.95 -3.13 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. Two gamma-ray sources listed in the 4FGL Fermi-LAT catalog are located within 2 deg of the best-fit candidate neutrino position. The sources are 4FGL J0151.3+8601 and 4FGL J0151.3+8601, both associated with BL Lac objects, and are located 1.5 and 1.7 deg away from the best-fit position, respectively. Both sources are also listed in the Fermi 3FHL catalog as 3FHL J0249.7+8434 and 3FHL J0148.4+8601, respectively. A total of 9 sources listed in the 4FGL catalog are contained in a 4 deg radius from the best-fit position, which approximately corresponds to the 90% containment radius 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 ------------------------------------------------------------------------------------ Erik Blaufuss email: blaufuss@umd.edu Department of Physics http://icecube.umd.edu/~blaufuss University of Maryland Phone: 301-405-6077 College Park, MD 20742 Office: PSC 2208E "Any chance collision, and I light up in the dark." ------------------------------------------------------------------------------------