Create a Clean Mask from Continuum Image or Moment Cube
If the morphology of your source is complicated, it can often be more efficient and reproducible to create a CLEAN mask from the data itself. This page outlines how to do this for continuum data (from the dirty image) and for spectral line data (from the moment 0 map of the dirty line cube).
Another useful resource is [[Masking Images for Analysis]]
---++ Creating a Mask from Continuum Data