The optical variability of 3C345

Photographic observations of the quasar 3C345 during 1968 and 1969 are reported. They show a quiescent state during 1968 and renewed activity in 1969. Fourier analysis of all available brightness measurements 1965–69 shows a dominant long-term variation with an apparent period of 1025 d, and two weak components with periods of 165 d and 556 d. There are no conspicuous short-period components down to 10 d. The light-curve synthesized from these three components does not fully represent the rapid variations, but does suggest a period of 165 d for the optical spikes, which is probably related to the periods of 80 d and 320 d suggested earlier.