TITLE: GCN CIRCULAR NUMBER: 30950 SUBJECT: AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-211020A DATE: 21/10/20 15:29:01 GMT FROM: Hugo Ayala at Pennsylvania State University <hgayala@psu.edu> The AMON, IceCube, and HAWC collaborations report: The AMON NuEm stream channel found a coincidence alert 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 6.02 hours. The HAWC transit interval starts from 10/20/2021 08:11:51 UT - 10/20/2021 14:13:37 UT (End of the HAWC transit time) The location of the coincidence is reported as RA (J2000): 99.76 deg Dec (J2000): 9.07 deg Location uncertainty (50% containment): 0.17 deg (statistical only). Location uncertainty (90% containment): 0.31 deg (statistical only). The false alarm rate (FAR) of this coincidence is 0.86 per year. We encourage follow-up observations of the alert region contingent on the 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 on the IceCube collaboration: http://icecube.wisc.edu/ Information on the HAWC collaboration: https://www.hawc-observatory.org