Optical and infrared polarimetry and photometry of blazars

We have carried out a polarization study of 44 blazars and candidate blazars at optical and near-infrared frequencies covering the period 1986 August to 1988 February. The data show flux and polarization properties changing on internight timescales, and commonly exhibit frequency dependence of a spectral index, polarization and polarization position angle. The observations of the quasar 1253 - 055(3C279) showed a U-band polarization of 45.5 ± 0.9%, the highest ever seen in a blazar. The interpretation of the data is the subject of a further paper (Ballard et al., 1989).