2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/5277We report on new measurements of the stellar velocity dispersion of 4 BL Lac objects for which optical spectroscopy was gathered at the ESO 3.6m using EFOSC2. Assuming the M(BH)--(sigma) relation is valid also for ellipticals hosting active nuclei we estimate the central BH mass of these BL Lacs.2 pages; Conference proceeding "Active Galactic Nuclei: From Central Engine tp Host Galaxy", Meudon, France, 23-27 July 2002; to be published in a special volume of the Astronomical Society of the Pacific Conference SeriesAstrophysicstext