Documentation on demos

Task: demos
Purpose: Inverse mosaicing operation
Categories: map manipulation

        DEMOS (de-mosaic) is a MIRIAD task which takes an input image, or
        cube, and forms output images by applying a primary beam. Several
        pointing centers are accepted, with a different output image
        formed for each pointing. Thus this task
        performs the inverse operation of mosaicing. The input pointing
        centres and the primary beam size are indirectly specified by
        a visibility dataset.

        Because the output of DEMOS are not primary beam corrected, they can
        be used for comparison with other uncorrected images and uvdata. In
        particular SELFCAL cannot handle a model which is primary beam
        corrected, though it can handle a visibility data file containing
        multiple pointings. Thus you could use DEMOS to break the model into
        several models which are not primary beam corrected.

Key: map
        This is the name of image, that is to be de-mosaiced. No default.
        The input is primary beam corrected image, single dish image, or
        one that is partially primary beam corrected (e.g. the output
        of MOSMEM).

Key: vis
        This is one or more input visibility datasets. The pointing centres
        and primary beams corresponding to the selected visibilities are used
        in the de-mosaicing process.

Key: select
        Normal uv selection. See help on select. Generally you will select
        only those pointings of interest.

Key: out
        This gives a template name for the output images. The actual output
        image names are formed by appending a number corresponding to each
        pointing center to this output name. For example, if out=cygnus,
        then the output images will be called cygnus1, cygnus2, etc.

Key: imsize
        This gives two values, being the output image size, in x and y.
        If no value is given, then the outputs will be one primary beam
        width in size. If one value is given, then this is used for both
        x and y. Each output size might be smaller than this, to prevent
        each output from extending beyond the edges of the input image.

Key: options
        Extra processing options. There is currently only one option.
          detaper    This indicates that the input image is not fully
                     primary beam corrected. Such images are formed by
                     LINMOS with options=taper or by MOSMEM.