OPTICAL POLARIZATION OF 52 RADIO-LOUD QSOS AND BL LACERTAE OBJECTS

Polarization measurements are presented for 52 radio-loud QSOs and BL Lac objects. For nine highly polarized (p > 3%) active galactic nuclei (AGNs), these are the first published polarization measurements. Of t hese nine, seven are highly polarized QSOs (HPQs), one is a BL Lac obj ect, and another is a likely BL Lac object. Polarization variability i s confirmed for some of these new and previously known highly polarize d AGNs. While six of the HPQs have flat radio spectra and are almost c ertainly blazars, PKS 1452-217 is probably a new member of the rare cl ass of radio-loud QSOs that show high polarization by scattering, and it is therefore important for testing orientation unified schemes. In competition for the highest redshift HPQ are the well-observed QSO PKS 0438-43 at z = 2.85, with maximum p similar to 4.7%, and PKS 0046 - 3 15 at z = 2.72, for which we find p similar to 13%.