Compiling the largest multiwavelength database of known changing-look AGN: Prospects in the Rubin era
Changing-look active galactic nuclei (CL-AGN) provide a direct way to study accretion and spectral-state changes on timescales of months to years. Still, the known population remains scattered across heterogeneous literature samples. We present a compilation of a homogenized catalog of known CL-AGN and related candidates, designed as a traceable reference database for time-domain and multiwavelength studies. After coordinate homogenization, duplicate removal, and validation, the optical parent catalog contains 1,438 unique sources, including 987 spectroscopically confirmed CL-AGN and 451 candidate or photometrically selected systems. We augment the catalog with ancillary information from radio/mm, infrared, ultraviolet, X-ray, and gamma-ray data sets using nway and survey-specific quality criteria. The resulting database includes 188 sources in the broad radio layer, 9 RFC/VLBI compact-core matches, 16 sources with ALMA archival coverage, 1,353 infrared counterparts, 918 GALEX ultraviolet matches, and 576 X-ray counterparts. We also identify 9 Fermi-LAT candidate associations. Overall, 1,385 sources have at least one non-optical counterpart, and 75 have coverage across the four main ancillary regimes: radio, infrared, ultraviolet, and X-ray. As a first application, we identify 70 confirmed CL-AGN within the LSST Wide--Fast--Deep footprint and 5 within the Rubin Deep Drilling Fields, and provide the up-to-date, ~116-day ugrizy Rubin lightcurve for SDSS J095902.76+021906.3 (z=0.34579) and discuss the early data inferences. This catalog is envisioned to be community-driven and provides a dynamic, expandable resource for target selection, population comparisons, and future Rubin-era CL-AGN studies.