uvcontsub is a task to perform continuum fitting and subtraction in the uv plane
This task estimates the continuum emission by fitting polynomials to the real and imaginary parts of the spectral windows and channels selected by fitspw. This fit represents a model of the continuum in all channels. The fitted continuum spectrum is subtracted from all channels selected in spw, and the result (presumably only line emission) is stored in a new MS that is always called vis + ".contsub". If an MS with the output name already exists, it will be overwritten.
uvcontsub will read from the CORRECTED_DATA column of vis if it is present, or DATA if it is not. Whichever column is read is presumed to have already been calibrated.
WARNING: Strictly speaking, the uvcontsub model is only a good representation of the continuum at the phase center. Residuals may be visible for sources far away and one may try imcontsub in the image domain for improved results. 

WARNING: fitorders > 1 are strongly discouraged because high order polynomials have more flexibility, may absorb line emission, and tend to go wild at the edges of fitspw, which is not what you want. default: 0 (constant)

If want_cont =True, the continuum fit is placed in a second new MS with the name vis + '.cont', also overwritten if it already exists. 
INFO:  because the continuum model is necessarily a smoothed fit, images made with it are liable to have their field of view reduced in some strange way. Images of the continuum should be made by simply excluding the line channels (and probably averaging the remaining ones) in tclean.

Parameter descriptions


Name of input MS. Output goes to vis + ".contsub" (will be overwritten if already exists)


Field selection for continuum estimation and subtraction. The estimation and subtraction is done for each selected field separately in turn. default: '' (all fields) (See Data Selection in a MeasurementSet)


Selection of spectral windows and channels to use in the fit for the continuum, using general MS selection syntax for spectral windows, e.g. in spw:chan format (spw ids are required but '*' can be used) or as frequencies. See the note under combine. default: fitspw=''  (all)

excludechans (fitspw subparameter)

if True, it will exclude the channels (or frequency range) that is specified in fitspw for the fit; this is useful to specify the line channels to exclude rather than the continuum channels to include in the fit. (default: False)


Continuum solutions will break at scan, field, and spw boundaries according to solint. To allow solutions across these boundaries, combine can be set to 'spw', 'scan', or 'spw, scan'.  combine must include 'spw'  if spw contains spws that are not in fitspw!  default: ''  which is that solutions will break at scan, field, and spw


Timescale for per-baseline fit (units optional) options are time ranges, e.g. '10s', or 'inf' per scan, or 'int' per integration. default (recommended): 'int', i.e. no time averaging, do a fit for each integration and let the noisy fits average out in the image.continuum fit. If solint is longer than 'int', the continuum estimate can be
corrupted by time smearing.


Polynomial order for the fits of the continuum w.r.t. frequency. fitorders > 1 are strongly discouraged because high order polynomials have more flexibility, may
absorb line emission, and tend to go wild at the edges of fitspw, which is not what you want. default: 0 (constant)


Optional per spectral window selection of channels to include in the output. See the note under combine. The sub-MS output spectral windows will be renumbered to start from 0, as in split. default: '' (all spws) (See Data Selection in a MeasurementSet)


Create vis + '.cont' to hold the continuum estimate.