TITLE: GCN CIRCULAR NUMBER: 27719 SUBJECT: IceCube-200512A: IceCube observation of a high-energy neutrino candidate event DATE: 20/05/12 10:58:22 GMT FROM: Cristina Lagunas Gualda at DESY The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 20/05/12 at 07:31:27.76 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 2.61 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/134081_58268464.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 20/05/12 Time: 07:31:27.76 UT RA: 295.18 (+1.72 -2.26 deg 90% PSF containment) J2000 Dec: 15.79 (+1.26 -1.29 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. There are no 4FGL sources inside the 90% localization region. The closest source is 4FGL J1947.1+1729 located at RA 296.78 deg and dec 17.49 deg (at a distance of 2.28 degrees from the best-fit location). 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