Can help to remove bowls around sources AST.ZERO_SNR_FWHM
"
ast.zero_snr"
. The final SNR-based
mask associated with this map is then smoothed using a Gaussian with FWHM equal
to the ast.zero_snr_fwhm value (in arcsec). The whole iterative map-making process is
then run again from the start, using this smoothed mask on every iteration, to create the
final map. Consequently, setting ast.zero_snr_fwhm causes the time taken to create the
final map to nearly double. [0.0]