Documentation on linmos

Task: linmos
Purpose: Linear mosaicing of datacubes
Categories: map combination

        LINMOS is a MIRIAD task which performs a simple linear mosaicing of
        input cubes, to produce a single output cube. If only a single
        input cube is given, LINMOS essentially does primary beam correction
        on this input. When several, overlapping, inputs are given, then
        LINMOS combines the overlapping regions in such a way as to minimize
        the expected mean error in the output. LINMOS can also be used to
        interpolate an image onto another pixel size and center.

        To determine the primary beam of the telescope, LINMOS first checks
        the map header for the presence of the "pbfwhm" parameter. If present,
        LINMOS assumes the primary beam is a Gaussian, whose FWHM (in arcsec)
        at the reference frequency, is given by the "pbfwhm" parameter. A
        single dish has a zero or negative value for pbfwhm. If
        the "pbfwhm" parameter is missing, LINMOS checks if the telescope
        is one that it knows. If so, then the best known form for the
        primary beam is used. Currently LINMOS knows about the VLA, the
        ATCA and the BIMA array.

        If the map neither has a pbfwhm parameter nor is it from a known
        telescope, LINMOS will refuse to do anything! In this case, you
        should add the pbfwhm parameter to the map header, using puthd.
        For example:
          % puthd in=mymap/pbfwhm value=120.0
        will set a primary beam FWHM of 120 arcsec at the reference frequency.

Key: in
        This gives the names of the input cubes. Many cubes can be given.
        There is no default. Inputs do not need to be on the same grid system
        on the x (RA) and y (DEC) dimensions. However, if they are not, linear
        interpolation is performed to regrid using the first image as the
        template. The intensity units of all the inputs, and the pixel size 
        and alignment of the third dimension are assumed to be the same.

Key: out
        The name of the output cube. No default. The center and pixel size
        of the first input image is used as the grid system of the output.

Key: rms
        The rms noise levels in the input cubes. The default is determined
        from the input images. If this is not possible for an image,
        then the rms of the previous image is used. If no value could be
        determined for the first image, all images are given equal weight.

Key: options
        Extra processing options. Several can be given, separated by
        commas. Minimum match is supported. Possible values are:
          taper        By default, LINMOS fully corrects for primary
                       beam attenutation. This can cause excessive noise
                       amplification at the edge of the mosaiced field.
                       The `taper' option aims at achieving approximately
                       uniform noise across the image. This prevents full primar
                       beam correction at the edge of the mosaic.
          sensitivity  Rather than a mosaiced image, produce an image
                       giving the rms noise across the field.
          gain         Rather than a mosaiced image, produce an image
                       giving the effective gain across the field. If the
                       "signal" parameter is allowed to default, the gain
                       function will be either 0 or 1 across the field.