HAWC's Eye - Implementing Hybrid Detection at the HAWC Gamma-Ray Observatory

Combining a compact imaging air-Cherenkov telescope with the High-Altitude Water Cherenkov Gamma-Ray Observatory (HAWC) promises significant improvements in energy resolution, angular resolution and background suppression. The HAWC Observatory is an extensive air-shower array located in the state of Puebla, Mexico, sensitive at TeV energies continuously monitors 2 sr of the sky. An improved sensitivity has the power to significantly increase the number of monitored sources. Triangulation by a compact air-Cherenkov telescope in a hybrid setup overcomes ambiguities on the height of the shower core if measured only with a ground array. A Cherenkov telescope prototype featuring a 50 cm Fresnel lens and a camera with 61 semi-conductor photo sensors (SiPM) was commissioned and temporarily installed at the HAWC site in summer 2017. For the first time, hybrid events were recorded and the energy threshold and other basic properties of the telescope were measured and compared with simulations. Results of this campaign will be presented.