A comparative study of the intra-night optical variability of powerful AGNs.

In order to address a currently much debated issue, we ate carrying out a systematic search for intra-night optical micro-variability in major classes of powerful (M[subv] ≥ -23.0 mag) active galactic nuclei (AGNs). Our sample includes 7 sets of AGNs, covering narrow redshift bins across the range 0.18 ≤ z ≤ 2.2 . Each set consists of a radio-quiet quasar, a radio lobe-dominated quasar, a BL Lac object and/or a radio core-dominated quasar (blazar), all having m[subv] ∼ 16 mag. The observations were made primarily using the 104-cm telescope of State Observatory, Nainital. The monitoring completed so far (∼ 90 nights) clearly indicates that, compared to the other AGN types, BL Lacs are distinctly more prone to exhibit intra-night optical variations. [ABSTRACT FROM AUTHOR]