TITLE: GCN CIRCULAR NUMBER: 30010 SUBJECT: AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEM-210515A and 210515B DATE: 21/05/15 03:15:53 GMT FROM: Hugo Ayala at Pennsylvania State University The AMON, IceCube, and HAWC collaborations report: The AMON NuEm stream channel found two coincidence alerts from the IceCube online neutrino selection + HAWC daily monitoring analysis. The analysis looks for IceCube neutrino events -mostly atmospheric in origin- around the position and transit time of a HAWC cluster of likely gamma rays, as identified in the integrated observations from a single transit, in this case having a duration of ~6 hours. NuEM-210515A The HAWC transit interval starts from 05-14-2021 18:06:02 UT to 05-15-2021 00:20:43 UT (End of the HAWC transit time) The location of the coincidence is reported as RA (J2000): 93.64deg Dec (J2000): 14.66 deg Location uncertainty (50% containment): 0.15 deg (statistical only). Location uncertainty (90% containment): 0.27 deg (statistical only). The false alarm rate (FAR) of this coincidence is 3.93 per year. NuEM-210515B The HAWC transit interval starts from 05-14-2021 18:09:25 UT to 05-15-2021 00:19:27 UT (End of the HAWC transit time) The location of the coincidence is reported as RA (J2000): 93.93deg Dec (J2000): 12.51deg Location uncertainty (50% containment): 0.20 deg (statistical only). Location uncertainty (90% containment): 0.36 deg (statistical only). The false alarm rate (FAR) of this coincidence is 1.90 per year. We encourage follow-up observations of the alert region contingent on availability of resources and interest, given the quoted FAR. AMON seeks to perform a real-time correlation analysis of the high-energy signals across all known astronomical messengers. More information about AMON can be found in https://www.amon.psu.edu/ Information of this analysis https://iopscience.iop.org/article/10.3847/1538-4357/abcaa4 Information on the IceCube collaboration: http://icecube.wisc.edu/ Information on the HAWC collaboration: https://www.hawc-observatory.org