Exclude regions of low RMS from sourcefinding
Exclude regions of low RMS from sourcefinding

These regions are "empty" regions of the image filled with garbage from
awimager. We'll just find false sources here, which are likely unfittable.

bartscheers/tkp,mkuiack/tkp,transientskp/tkp,mkuiack/tkp,transientskp/tkp,bartscheers/tkp