[CLEAN\]FIT [Plane] | [CHANNEL First Last] [FIELD First Last]
[/THRESHOLD Value] /JVM_FACTOR [NoCircle]
This option instructs the FIT command to estimate the so-called JvM fac-
tor (from Jorsater van Moorsel 1995), which is the ratio of Clean beam
area to Dirty beam area. The value is returned into the BEAM_JVM vari-
able.
The Dirty beam area is an ill-defined quantity (if no Zero spacing is
included, the Dirty beam area tends toward Zero when a sufficiently
large area is included). It is defined here by integrating only up to
the first null of the Dirty beam.
In case of Dirty beams presenting shoulders around the main beam, this
ratio may be used to adjust the contribution of residuals to the CLEAN
image so that the flux is better preserved. For well-behaved beams, it
should be quite close to 1.
NoCircle is an argument which, if present, indicates that the Clean and
Dirty beam should not be circularized to derive the factor; this should
be reserved for debugging.
Gildas manager
2023-06-01