Аннотация:Abstract
The UBV observations of the variable radio source LSI+61o303 carried out at the Crimean Station of the Sternberg Astronomical Institute in 1989-1990 and 1999-2002 are presented. We constructed a combined light curve of the star spanning 6400 days from our and published data. Slow brightness variability with an amplitude of 0.1 mag was detected. Using the entire combined series, we searched for a periodicity in a frequency range close to the radio period P = 26.5 days. The optical period was found to be exactly equal to the radio period. The shape and amplitude of the mean curves constructed with the radio period change from V to U: the detected double wave shows up most clearly in the U band.