Аннотация:The light variability of the X-ray source has been studied using photographic plates and UBV electrophotometry. An improved value of the orbital period has been found, which is consistent with all the light fadings during 1909-1991. It is suggested on the basis of photographic observations that the depth of the minimum varies from 0.4 to 0.1 m. The position of the object on the two-color diagram is shown.