Correction for angular acceptance of the TAIGA-HiSCORE

TAIGA-HiSCORE is an array of wide-angle air-Cherenkov detectors distributed on the area of 1 km${}^2$. It is a part of a hybrid gamma-ray observatory TAIGA which combines imaging and timing techniques to detect Cherenkov emission from the extensive air showers. To collect Cherenkov light TAIGA-HiSCORE uses light guides —Winston cones—combined with PMTs. We present the results of measurements of angular acceptance of PMT+cone unit and entire TAIGA-HiSCORE installation. Orientation of the dynode system in the PMT makes the PMT+cone unit angular characteristic asymmetric. This asymmetry is combined with another one caused by the detector orientation with respect to the zenith. It determines the angular acceptance of the installation. Asymmetric angular characteristic distorts a signal of initial event flux—distribution of detected events. To obtain an original signal this distortion should be corrected using appropriate weight functions according to the certain energy range. With energy increase distribution of detected events becomes more uniform. Obtained results can be used for estimation of cosmic ray background, simulation of the TAIGA-HiSCORE detectors and for hybrid operation of the two installations.