The characterisation of a cerenkov imaging telescope for ground-based gamma-ray astronomy through correlation of coincident images

The Cerenkov installation of the Crimean Astrophysical Observatory, consisting of two identical detectors, separated by 20m, are mounted in parallel for comparing the parameters of images. The average counting rate at one section is 35% higher than at the other. The number of coincident flashes make up 55% for one section and 76% for the second section. The comparison of parameters of coincident events shows high correlation of centroid positions (correlation coefficient r=0.98), of length (r=0.70), orientational angle (r=0.64). The correlation of width parameters is considerably lower (r=0.44).Since the coincident flashes at the two sections correspond to the same EAS their image parameters must be the same or very close. Hence the correlation coefficient between identical parameters of coincident flashes will characterize the quality of equipment and the method of observational data processing.