An optical polarization survey for BL Lacertae objects and highly polarized quasars

We present the results of an extensive optical survey for highly polarized objects. The survey is complete to a B magnitude of 20 and covers 560 square degrees. We did not find any confirmed BL Lac objects, highly polarized quasars, or blazars, but we are able to constrain the surface density of the various populations of linearly polarized objects. Our constraints on the numbers of a population of polarized objects are a function of the duty cycle and the degree of polarization of the objects being constrained. We rule out the presence of an abundant population of radio-quiet BL Lacertae objects.