الخلاصة

The aim of research is to calculate the photon counting out put from CCD camera by indication of luminous flux arrived to the CCD camera in Perkins telescope at Lowell observatory ,stars of wide range magnitude are included through UBVRI filter system by take into account the limits of smallest magnitude for the system . Tables of photon counting versus magnitude has taken as indicators to the Precision of practical observation values which registered by the system thus the observer be able to know the right observation.