Setting this parameter to a non-zero value causes the SNR mask requested by parameter "ast.zero_snr" to be created using an algorithm like that used by the KAPPA command " FFCLEAN" (see SUN/95), instead of using a simple thresholding of the SNR map. The parameter "ast.zero_snr" gives the clipping level of the ffclean algorithm, and the parameter "ast.zero_snr_hipass" gives the box size. Using an ffclean algorithm prevents the source regions within the mask being larger than the box size, and may thus produce faster convergence and avoid blobs developing. [0]

MAKEMAP, CALCQU