Overlays

This contains one or more plots which can be of three types:

Experimental plots (numerical data typically in the form of frequency,intensity pairs)
Bitmaps (a picture copied or scanned where the raw data is not available.)
Calibration plots, containing built in line lists - see Calibrating Spectra.

For more information see the overlays window. Note that a Variables object (to hold dummy parameters for constrained fits) can also be added to the Overlays object. A few settings apply to the overall set of plots:

Settings

Units	Units for plot.
IntensityUnits	Selects vertical units for plot. If you use "Arbitrary" or "Squared" here, then the plot will always be scaled to the full range available. Note that if the experimental data has a non-zero baseline then the units should be set to "Arbitrary" to avoid problems with conversions of intensity scales.
ContourFile	If set, read an external text observation file when contour fitting, typically to set constraints. This is in addition to using any Experimental plots loaded. The file should be set in the log window, as for line position fits.
`nComponents`	(Future use)

Parameters

PeakThreshold

Threshold for peak finder.