TITLE: GCN CIRCULAR NUMBER: 24864 SUBJECT: IceCube-190619A - HAWC follow-up DATE: 19/06/20 14:21:26 GMT FROM: Israel Martinez-Castellanos at UMD/HAWC Antonio Galván (IA-UNAM), Israel Martinez-Castellanos (UMD) and Ignacio Taboada (GaTech) report on behalf of the HAWC collaboration (http://www.hawc-observatory.org/collaboration/): On June 19, 2019, 13:14:18.04 UT, the IceCube collaboration reported a track-like very-high-energy event that has a high probability of being an astrophysical neutrino, IceCube-190619A, at RA 343.26 deg and Dec 10.73 deg, J2000 (GCN circular 24854). In HAWC's sky, the neutrino was at zenith of 26.44 deg and setting. We have searched for a steady source as well as a transient source. * Search for a steady source in archival data from November 2014 to May 2018. Assuming a spectral index of -2.3 we searched in a 4.08 degree circle around IceCube's reported location. The highest significance, 3.02 sigma, was at RA= 344.88 deg, Dec= 13.28 deg (J2000). Note that there are at least 200 trials in this search, so post-trials significance is lower. We set a time-integrated upper limit 95% CL on gamma rays of: E^2 dN/dE = 2.59e-13 (E/TeV)^-0.3 TeV cm^-2 s^-1 * Search for a transient source. We have studied the transit of the event in HAWC's field of view (start 2019/06/19 08:30:06 UTC / stop 2019/06/19 14:37:06 UTC). The most significant location, within 4.08 deg, is 3.44 sigma (RA = 338.93 deg, Dec = 9.99 deg, J2000). We set a time-integrated upper limit 95% CL on gamma rays of: E^2 dN/dE = 1.56e-11 (E/TeV)^-0.3 TeV cm^-2 s^-1 HAWC is a very-high-energy gamma-ray observatory operating in Central Mexico at latitude 19 deg. north. Operating day and night with over 95% duty cycle, HAWC has an instantaneous field of view of 2 sr and surveys 2/3 of the sky every day. It is sensitive to gamma rays from 300 GeV to 100 TeV.