Difference between revisions of "Uvcontsub"

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{{uvcontsub}}
Help on uvcontsub task:
 
 
 
Continuum fitting and subtraction in the uv plane
 
 
 
       
 
        A polynomial of the desired order is fit to each baseline/time across the
 
        specified channels that define the continuum emission.  The data may
 
        be averaged in time to increase the signal to noise.  This fit
 
        represents a uv-data model of the continuum across all channels.
 
       
 
        For fitmode='subtract', the fitted continuum uv spectrum is
 
        subtracted from all channels and the result (presumably only
 
        line emission) is stored in the CORRECTED_DATA.  The
 
        continuum fit is stored in the MODEL_DATA.
 
 
 
        For fitmode='model' the continuum model is stored in the
 
        MODEL_DATA; but the CORRECTED_DATA is unaffected.
 
 
 
        For fitmode='replace' the continuum model is stored in
 
        the CORRECTED_DATA; this is useful to image the continuum model
 
        result.  You will have to rerun applycal to place the calibrated
 
        data back in the CORRECTED_DATA
 
 
 
        Keyword arguments:
 
        vis -- Name of input visibility file
 
                default: none; example: vis='ngc5921.ms'
 
        field -- Field selection
 
                default: field = '' means select all fields
 
                field = 1 # will get field_id=1 (if you give it an
 
                        integer, it will retrieve the source with that index.
 
                field = '1328+307'  specifies source '1328+307'
 
                field = '13*' will retrieve '1328+307' and any other fields
 
                  beginning with '13'
 
        fitspw -- Selection of spectral windows and channels to use in the
 
                  fit for the continuum, using general spw syntax
 
                default: ''=all; example: fitspw='0:5~30;40~55'
 
        spw -- Optional per spectral window selection of channels from
 
              which to subtract the continuum.
 
                default: spw='', means subtract from all channels for
 
                  each spw that had a continuum estimated
 
              Also, this specifies which spw/chan will be split
 
              out if splitdata=True.
 
        solint -- Timescale for per-baseline fit (units optional)
 
                default: 'int' --> no averaging, fit every integration;
 
                example: solint='10s'  --> average to 10s before fitting
 
                        10 or '10' --> '10s' (unitless: assumes seconds)
 
                options: 'int' --> per integration
 
 
 
        Keyword arguments:
 
        vis -- Name of input visibility file
 
                default: none; example: vis='ngc5921.ms'
 
        field -- Field selection
 
                default: field = '' means select all fields
 
                field = 1 # will get field_id=1 (if you give it an
 
                        integer, it will retrieve the source with that index.
 
                field = '1328+307'  specifies source '1328+307'
 
                field = '13*' will retrieve '1328+307' and any other fields
 
                  beginning with '13'
 
        fitspw -- Selection of spectral windows and channels to use in the
 
                  fit for the continuum, using general spw syntax
 
                default: ''=all; example: fitspw='0:5~30;40~55'
 
        spw -- Optional per spectral window selection of channels from
 
              which to subtract the continuum.
 
                default: spw='', means subtract from all channels for
 
                  each spw that had a continuum estimated
 
              Also, this specifies which spw/chan will be split
 
              out if splitdata=True.
 
        solint -- Timescale for per-baseline fit (units optional)
 
                default: 'int' --> no averaging, fit every integration;
 
                example: solint='10s'  --> average to 10s before fitting
 
                        10 or '10' --> '10s' (unitless: assumes seconds)
 
                options: 'int' --> per integration
 
                        'inf' --> per scan
 
        fitorder -- Polynomial order for the fit of the continuum
 
                default: 0 (constant); example: fitorder=1
 
        fitmode -- Use of the continuum fit model
 
                default: 'subtract'; example: fitmode='replace'
 
                Options:
 
                'subtract'-store fitted continuum model in MODEL and
 
                  subtract this continuum from data in CORRECTED to
 
                  produce line-emission in CORRECTED.
 
                'model'-store fit continuum model in MODEL, but
 
                  do not change data in CORRECTED.
 
                'replace'-replace CORRECTED with continuum mode fit.
 
        splitdata -- Split out continuum and continuum subtracted line data
 
                default: 'False'; example: splitdata=True
 
                The derived continuum data will be placed in: vis.cont
 
                The continuum subtracted data will be placed in: vis.contsub
 
                The spw/channels selected are given in spw
 
        async -- Run task in a separate process (return CASA prompt)
 
                default: False; example: async=True
 
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Latest revision as of 13:29, 3 December 2014