Improve the estimate of the common-mode by excluding samples that correspond to high SNR pixels in the map
"
com.zero_snr_ffclean"
.
Note, the SNR values are only available once a map has been created, and so using this parameter results in no
COM masking on the first iteration. Consequently the map at the end of the first iteration will have a bowl
around any bright sources, since no COM masking was done. Normally, these rings would polute the AST
model derived from the map, and thus polute the residuals on the next iteration, resulting in the bowls
remaining in later maps. To avoid this, parameter "
ast.skip"
can be set to a positive value. This causes the AST
model to be skipped (i.e. no AST signal is subtracted from the residuals) for the first "
ast.skip"
iterations. This means that a good COM mask can be formed from these initial iterations before
any AST model is calculated and used. [0.0]