Skip subtraction of astronomical signal


If ast.skip is non-zero, it gives the number of initial iterations for which no AST model (astronomical signal) should be subtracted. A map is still formed at the end of these iterations but the astronomical signal implied by this map is not removed from the residuals (neither is it added back prior to forming the next map). This means that the residuals at the start of each of these iterations are unchanging and essentially equal to the cleaned raw data. The value supplied for parameter "numiter" should therefore be greater than the value of " ast.skip" .

This option is useful, for instance, when using SNR-based masking for the FLT and/or COM models, since it allows a reasonable mask to be formed before subtracting off the first estimate of the astronommical signal.

If ast.skip is set to a negative value, it gives the largest number of iterations to perform and indicates that the AST model should be skipped on all of them. In this case the value supplied for parameter "numiter" is ignored. [0]