Basic Information on demos

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

        DEMOS (de-mosaic) is a MIRIAD task that takes a model of the sky
        (that is primary beam corrected), and multiplies by a primary
        beam response function at a number of different pointing
        centers.  It produces a different output for each pointing
        center.  Thus this task performs the inverse of mosaicing.  The
        input pointing centers and the primary beam size are indirectly
        specified by a visibility dataset.
 
        Because the output of DEMOS have primary beams applied, they can
        be used for comparison with visibility data and uncorrected
        images.  In particular SELFCAL cannot handle a model that 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 the image to be de-mosaiced.  A primary beam
        corrected image, single dish image, or one that is partially
        primary beam corrected (e.g. the output of MOSMEM).  No default.

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.
 
Revision: 1.8, 2014/05/21 04:34:59 UTC