CASA Contributed Task: findsources
From CASA Guides
findsources: use the online Vizier catalogs to find sources for outlier-field imaging
Download task files: File:Task findsources.py, File:Findsources.xml
This task queries any VizieR catalog around coordinates defined by either the phase center of a source in the input visibility file or an input RA/Dec pair. It creates an outlier file which can be used by clean to create images of flanking fields. This is particularly useful if there is a bright source relatively nearby which would create imaging artifacts if ignored. (Note that some catalog abbreviations are ambiguous: in this case, use the full catalog name, or VizieR will query multiple catalogs.)