casa6

​

                        A common usage is to set this parameter equal to a single dish image

​

                        Negative components in the model image will be included as is.

​

      </description>

      <value type="string"/>

    </param>

​

    <!-- TODO in CAS-13570: fix asp description and allow asp value once asp is working -->

    <param type="string" name="deconvolver">

      <shortdescription>Minor cycle algorithm (hogbom,clark,multiscale,mem,clarkstokes)</shortdescription>

      <!-- <shortdescription>Minor cycle algorithm (hogbom,clark,multiscale,mtmfs,mem,clarkstokes,asp)</shortdescription> -->

      <description>Name of minor cycle algorithm (hogbom,clark,multiscale,mem,clarkstokes)

​

                        Each of the following algorithms operate on residual images and psfs

                        from the gridder and produce output model and restored images.

                        Minor cycles stop when threshold or niter are reached. For all

                        methods, components are picked from the entire extent of the image or

                        mem : Maximum Entropy Method [Cornwell and Evans, 1985]

                                - Iteratively solve for values at all individual pixels via the

                                  MEM method. It minimizes an objective function of

                                  chi-square plus entropy (here, a measure of difference

                                  between the current model and a flat prior model).

​

                                (Note : This MEM implementation is not very robust.

                                             Improvements will be made in the future.)

​

                        asp : This deconvolver is not currently considered reliable when used with

                              task deconvolve and is therefore disabled. Please choose a different

                              deconvolver.

​

​

​

      </description>

      <value type="string">hogbom</value>

      <allowed kind="enum">

        <value>hogbom</value>

        <value>clark</value>

        <value>clarkstokes</value>

        <value>clark_exp</value>

        <value>clarkstokes_exp</value>

        <value>multiscale</value>

        <value>mem</value>

        <!-- <value>asp</value> -->

​

      </allowed>

    </param>

​

    <param type="any" name="scales" subparam="true">

      <shortdescription>List of scale sizes (in pixels) for multi-scale algorithms</shortdescription>

      <description>List of scale sizes (in pixels) for multi-scale and mtmfs algorithms.

                        This set of scale sizes should represent the sizes

                        comparable to the scale corresponding to the lowest measured

                        spatial frequency (as a scale size much larger than what the

                        instrument is sensitive to is unconstrained by the data making

                        it harder to recovery from errors during the minor cycle).

      </description>

      <type>intVec</type><type>doubleVec</type>

      <value type="intVec"/>

    </param>

​

      <shortdescription>Number of Taylor coefficients in the spectral model</shortdescription>

      <description>Number of Taylor coefficients in the spectral model

​

                        - nterms=1 : Assume flat spectrum source

                        - nterms=2 : Spectrum is a straight line with a slope

                        - nterms=N : A polynomial of order N-1

​

                        From a Taylor expansion of the expression of a power law, the

                        spectral index is derived as alpha = taylorcoeff_1 / taylorcoeff_0

​

                                  two noisy numbers (alpha = xx.tt1/xx.tt0) where the

                                  'error' on tt1 and tt0 are simply the values picked from

                                  the corresponding residual images. The absolute value

                                  of the error is not always accurate and it is best to interpret

                                  the errors across the image only in a relative sense.)

​

​

      </description>

      <value type="int">2</value>

​

    <param type="double" name="smallscalebias" subparam="true">

      <shortdescription>Biases the scale selection when using multi-scale or mtmfs deconvolvers </shortdescription>

      <description>A numerical control to bias the scales when using multi-scale or mtmfs algorithms.

                        The peak from each scale's smoothed residual is

                        multiplied by ( 1 - smallscalebias * scale/maxscale )

                        to increase or decrease the amplitude relative to other scales,

                        before the scale with the largest peak is chosen. 

                        Smallscalebias can be varied between -1.0 and 1.0. 

                        A score of 0.0 gives all scales equal weight (default). 

      <when param="deconvolver">

        <equals type="string" value="hogbom">

        </equals>

        <equals type="string" value="clark">

        </equals>

        <equals type="string" value="multiscale">

          <default param="scales"><value type="intVec"/></default>

          <default param="smallscalebias"><value>0.0</value></default>

        </equals>

          <default param="scales"><value type="intVec"/></default>

          <default param="nterms"><value type="int">2</value></default>

          <default param="smallscalebias"><value>0.0</value></default>

        <!-- TODO in CAS-13570: uncomment once asp is working -->

        <!-- <equals type="string" value="asp">

          <default param="fusedthreshold"><value>0.0</value></default>

          <default param="largestscale"><value>-1</value></default>

        </equals> -->

      </when>

​

      <when param="restoration">

        <equals type="bool" value="True">

          <default param="restoringbeam"><value type="stringVec"/></default>