Reduces spurious large scale structure in the final map - an experimental alternative
or addition to AST masking AST.FILT_DIFF
If "
ast.filt_diff"
is non-zero it gives the size of the largest features to be retained, in arc-sconds (a value
equal to half of the FLT filter size seems to be a good starting point). At the end of each iteration the
difference is taken between the new map and the previous map. This difference is filtered using a
sharp-edged high-pass filter, of size specified by "
ast.filt_diff"
. The remaining high frequencies (i.e.
small structures that have been introduced by the new iteration) are added back onto the map
created by the previous iteration. This modified map is then used, instead of the original
map, to define the AST model. [0.0]