This is the minimal flux in the dirty map that the program will consider as significant. Alternatively, the threshold can be specified as a fraction of the peak flux using CLEAN_FRES. Once this level has been reached the program stops subtracting, and starts the restoration phase. The unit for this parameter is the map unit (typically Jy/Beam). The parameter should usually be of the order of magnitude of the expected noise in the clean map.
If 0, CLEAN_FRES will be used instead. If all of CLEAN_NITER, CLEAN_ARES and CLEAN_FRES are 0, an absolute residual equal to the noise level will be used for CLEAN_ARES.
Short form is ARES.
This may be overseded by the /ARES option which imposes a limit per plane through an array of values.