The connection between the activity of the quasar 3C 345 in the optical and radio ranges

For the quasar 3C 345, a cross-correlation analysis is carried out of the data on optical and radio variability over long (of the order of hundreds of days) time scales. A high degree of correlation is found between the radio outbursts and the ''slow'' component (the characteristic time of variation being around 1 yr) in the optical brightness variations, the radio outbursts lagging behind by 7001000 days. A comparison of the magnitude of the lag with the apparent ''superluminal'' velocity of the radio components of the millisecond structure of 3C 345 enables to estimate the distance form the nucleus of the region in which the radio emission arises (/tau/ about 0''.7 x 10/sup -3/).