Optical spectroscopy of 1 Jy BL Lacertae objects and flat spectrum radio sources.

Optical spectroscopy is reported for a number of flat spectrum radio sources, most of which are either classified as BL Lacertae objects or have been described as BL Lac candidates. We present a total of ten new redshifts, confirm the suggested redshifts for three objects and give spectroscopic data for eight additional objects with already known redshifts. A variety of emission features and emission line strengths is found reaching from strong lines characteristic for high redshift quasars to very weak lines typical for classical BL Lac objects.