We report a relation between radio emission in the inner jet of the Seyfert galaxy ( catalog 3C~120 ) and optical continuum emission in this galaxy .
Combining the optical variability data with multi-epoch high-resolution very long baseline interferometry observations reveals that an optical flare rises when a superluminal component emerges into the jet and its maxima is related to the passage of such component through the location a stationary feature at a distance of \approx 1.3 parsecs from the jet origin .
This indicates that a significant fraction of the optical continuum produced in ( catalog 3C~120 ) is non-thermal and it can ionize material in a sub-relativistic wind or outflow .
We discuss implications of this finding for the ionization and structure of the broad emission line region , as well as for the use of broad emission lines for determining black hole masses in radio-loud AGN .