Region Files

Regions (region)

The region parameter points to a CASA region which can be directly specified or listed in a ImageRegion file. An ImageRegion file can be created with the CASA viewer’s region manager, or directly using the CASA region file (crtf) syntax. Typically ImageRegion files will have the suffix ".crtf" for CASA Region Text Format.

Alert: When both the region parameter and any of box/chans/stokes are specified simultaneously, the task may perform unwanted selections. Only specify one of these (sets of) parameters. We recommend the use of CASA regions and may remove the box/chans/stokes selection in later releases.

For example:

region='circle[[18h12m24s, -23d11m00s], 2.3arcsec]'



to specify a region file. For the most part, the region parameter in tasks only accepts strings (e.g. file names, region shape descriptions) while the region parameter in ia tool methods only accepts python region dictionaries (e.g. produced using the rg tool).

Alert: Some region file specifications are not (yet) recognized by the viewer.