TITLE: GCN CIRCULAR NUMBER: 25238 SUBJECT: IceCube-190730A - HAWC follow-up DATE: 19/07/31 21:11:35 GMT FROM: Antonio Galvan at Inst.de Astronomia,UNAM Antonio Galvan (IA-UNAM), Israel Martinez-Castellanos (UMD) and Jose Andres Garcia-Gonzalez (IF-UNAM) reports on behalf of the HAWC collaboration ( http://www.hawc-observatory.org/collaboration/): On 2019-07-30 at 20:50:41.31 UTC, the IceCube collaboration reported a track-like event with a moderate probability of being of astrophysical origin, IceCube-190730A, at RA= 225.79 deg and Dec= +10.47 deg, J2000 (GCN circular 25225). In HAWC's sky, the neutrino was at zenith of 60.74 deg and outside of our field of view. We have performed a search in our archival data 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 power law with a spectral index of -2.3 we searched in a 1.43 x 1.14 degree rectangle around IceCube's reported location. The highest significance, 2.38 sigma, was at RA= 226.54 deg, Dec= 10.35 deg (J2000). Note that there are at least 27 trials in this search, so post-trials significance is lower and equal to 0.712. We set a time-integrated upper limit 95% CL on the gamma-ray flux of E^2 dN/dE = 2.418e-13 (E/TeV)^-0.3 TeV cm^-2 s^-1. * Search for a transient source: Since the events was not in our field of view at the time reported on the GCN we did a search for the day before and after as well. The results are the following: 1.) 2019-07-29 Transit starts on 2019-07-29 22:00:36 and ends 2019-07-30 04:06:48 (UTC), 0.75 sigma pre-trials (0 post trials), was at RA= 225.64 deg, Dec= 9.86 deg (J2000). We set a time-integrated upper limit 95% CL on the gamma-ray flux of: E^2 dN/dE = 1.013e-11 (E/TeV)^-0.3 TeV cm^-2 s^-1. 2.) 2019-07-30 Transit starts on 2019-07-30 21:56:40 and ends 2019-07-31 04:02:52 (UTC), 1.76 sigma pre-trials (0 post trials), was at RA= 225.51 deg, Dec= 10.73 deg (J2000). We set a time-integrated upper limit 95% CL on the gamma-ray flux of: E^2 dN/dE = 1.251e-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.