TITLE: GCN CIRCULAR NUMBER: 22114 SUBJECT: HAWC follow-up of IceCube-171106A DATE: 17/11/09 22:42:33 GMT FROM: Simone Dichiara at UNAM Simone Dichiara (UNAM-IA), Israel Martinez (University of Maryland), J.A. García-González (UNAM-IF), Ignacio Taboada (Georgia Tech) report on behalf of the HAWC collaboration (https://www.hawc-observatory.org/collaboration/): On 2017/11/06 18:39:39.21 UT IceCube detected a track-like, very-high-energy event with a high probability of being of astrophysical origin, at RA=340.00d and Dec=+7.40d J2000 as reported in GCN circular 22105. The event was not in the field of view of HAWC, so we analyze the data following two different approaches: *We searched for a steady source in archival data from November 2014 to September 2017. Assuming a spectral index of -2.5 we searched in the reported 90% PSF containment circle.The maximum significance is 1.57 sigma at RA=339.48deg and Dec=7.78deg. We estimate the number of trials to be ~20. We set an upper limit 95% CL on gamma rays for this period of: E^2 dN/dE = 4.60e-13 (E/TeV)^-0.5 TeV cm^-2 s^-1. *We also performed a study using data corresponding to the two nearest transits of IceCube-171106 in HAWC’s field of view (MJD 58062.96-58063.22 and 58063.95-58064.21). Using the same spectral index and search window, the maximum significance is 1.2 sigma at RA=340.35deg and Dec=7.12deg. We set an upper limit 95% CL on gamma rays for this period of: E^2 dN/dE = 9.38e-12 (E/TeV)^-0.5 TeV cm^-2 s^-1. HAWC is a very-high-energy gamma-ray observatory located in Central Mexico at latitude 19 deg North. It operates 24 hours per day 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.