ESO VLT Optical Spectroscopy of BL Lac Objects IV

摘要

Among Active Galactic Nuclei BL Lacertae objects are charac-terized by the extreme weakness or complete absence of lines in their optical spectra. This hinders the measurement of their redshift, making it difficult to model and study the intrinsic properties of this class of objects. Here we report new results from an ongoing program of high S/N optical spectroscopy of BL Lacs performed with the ESO VLT under non-optimal sky conditions.