SIMBAD references

Optical polarization observations are presented of two low-luminosity flat-spectrum radio sources with optical broad lines. Both objects have significantly polarized optical continuum. The polarization is diluted by the Hα broad line, and must therefore be at least partly a continuum phenomenon. The objects therefore have all the properties of classical BL Lac objects, except, like BL Lac itself, they display significant broad lines for at least some of the time. The finding further blurs the distinction between BL Lac objects and other types of low-redshift, radio-loud active galaxies.