Miriad's CLEAN task - surprisingly called clean - implements the Högbom, Clark and SDI algorithms. Given an input dirty image and beam, it produces an output CLEAN component image which has flux density units of Jy/pixel. This CLEAN component image is CLEAN's best guess at what the source really looks like. Invariably its extrapolation at high spatial frequencies is very poor (and probably a reason why AIPS does not make it easy to view it). To reduce the undesirable effects of this extrapolation, and to add in any emission remaining in the residuals, you will need to use the task restor. This gives you what is normally thought of as the `CLEAN' or restored image.

The various input parameters to clean are:

Typical inputs are given below:

map=vela.imap Dirty image
beam=vela.ibem Dirty beam
out=vela.icmp Output CLEAN component image
mode Algorithm used - let CLEAN decide
region Defaults to max area safely CLEANed.
gain=0.1 Loop gain
phat Unset means no Prussian helmet
cutoff=0 Terminate CLEAN at this residual level or
niters=500 Specify total number of CLEAN components
speed Speedup factor; -1 for extended
  sources, +1 for point sources
minpatch=127 Minimum beam size for minor cycles
clip SDI clip level

The total CLEANed flux density (i.e. the cumulative sum of the CLEAN components) should eventually settle down to a roughly constant number. This indicates that you are just picking up noise, and that there are no sidelobes left to remove. If the total CLEANed flux density starts to decrease again, this usually indicates that you have been a bit heavy handed, and CLEANed too much. You might also look at the result and see if you can see any sidelobes left over.

Having completed clean, you will almost certainly want to ``restore'' your image - see Section 14.6.

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