Long-term optical photometric and polarimetric monitoring of 3C 66A

We present extensive photometric and polarimetric data sets of the blazar 3C 66A obtained from monitoring observations at Astronomical Institute of St.-Petersburg University and at Dodaira Observatory during 1974-1997. These data cardinally improved the optical light curve of 3C 66A and reliably determine some features and peculiarities in the behaviour of its optical polarization that we discuss in the context of the small amplitude of optical variability of 3C 66A and the structure of its milliarcsecond jet.