VLBA Imaging Polarimetry of Active Galactic Nuclei: An Automated Approach

We present full polarization Very Long Baseline Array (VLBA) observations at 5 and 15 GHz of 24 compact active galactic nuclei (AGNs). These sources were observed as part of a pilot project to demonstrate the feasibility of conducting a large VLBI survey to further our understanding of the physical properties and temporal evolution of AGN jets. The sample is drawn from the Cosmic Lens All-Sky Survey (CLASS) where it overlaps with the Sloan Digital Sky Survey at declinations north of 15°. There are 2100 CLASS sources brighter than 50 mJy at 8.4 GHz, of which we have chosen 24 for this pilot study. All 24 sources were detected and imaged at 5 GHz with a typical dynamic range of 500 : 1, and 21 of 24 sources were detected and imaged at 15 GHz. Linear polarization was detected in eight sources at both 5 and 15 GHz, allowing for the creation of Faraday rotation measure (RM) images. The core RMs for the sample were found to have an average absolute value of 390 ± 100 rad m-2. We also present the discovery of a new compact symmetric object, J08553+5751. All data were processed automatically using pipelines created or adapted for the survey.