|log=ic4296.maxfit||Write results to log file|
In this example, we fit a Gaussian to a region of an image by inputting
the region in a file. The file was generated interactively by
(see Chapter 17); you delineate a polygonal
region around the source of interest with a cursor. The quality of your
fit can improve significantly by selecting a snug region, and/or using
clip keyword to keep pixel values with little signal (e.g.
sidelobes and noise) out of the fitting process.
|clip=0.1||Only use pixels greater than 0.1|
|in the fitting process|
|object=gaussian||Fit a single gaussian|
|spar||Unset to let task set initial guess|
|fix||Unset to let everything float|
|out=ic4296.model||Write residuals of fit out to a dataset|
can fit multiple components. In this case, you
will need to set good initial estimates of the source parameters with
spar keyword, and good values for
become more important.
Note that if you specify a coordinate in km/s then the keyword stype indicates what convention that coordinate is in (radio or optical). You can specify the spectral-axis coordinate in any of frequency and the two velocity conventions, regardless of what the header says the spectral axis is; all spectral axis conversions are done as needed. In addition, any spectral-axis coordinate is converted to each of frequency, and optical and radio convention velocities (if possible).
See the help file for all the choices.
|type=arcsec,abspix,abskms||Input coordinate types|
|stype=radio||Velocity is in radio conventions|