A Project for a New Echo-Mapping Campaign at Intermediate Redshift

AGN masses can be estimated by "single epoch" spectral measurements through a mass-luminosity- linewidth relation calibrated by echo mapping measurements of a reference sample of low redshift ($z < 0.3$) and low luminosity ($M_B > -26$) AGNs. To analyze the possible dependence of this relation on luminosity we selected a sample of bright, intermediate redhift ($z \sim 1$) objects and we started a spectrophotometric monitoring campaign with a typical sampling time of about one month. Variability observations of lines with shorter wavelength than H$_\beta$ will also provide new information on the structure of the broad line region. Cross-correlation analysis of continuum and line variations will require years of monitoring. We present a preliminary analysis of the data collected during the first year of observations and we discuss the adequacy of the spectrophotometric accuracy attained and future prospects of this project.