MAP_REFINE
Keywords: map

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MAP_REFINE

             Task to "refine" the imaging process.

         The  zeroth  order  in imaging is to compute a single gridding and beam
        for all channels, at the center frequency: this is the standard  way  of
        making imaging. Strictly speaking, it produces an angular scale inverse-
        ly proportional to frequency. This is obtained by setting ONEBEAM$ to NO
        (and BCOL$ = 0) in the imaging tasks.
         The  infinite  order  is  to  compute one beam per channel, obtained by
        stting ONEBEAM$ to YES, but it is a costly process as gridding is to  be
        redone for each channel.

          This  task is here for the first order correction of the angular scale
        varying with frequency, just making a linear interpolation  between  im-
        ages  computed with two different gridding because of the angular scale.
        The images (or beams) are assumed to be computed for the frequencies  of
        the 2 extreme channels.

          These  files  (.lmv  and  .beam)  can be prepared by running twice the
        tasks UV_MAP or UV_INVERT with parameter BCOL$ set to 1 and  the  number
        of channels respectively on each execution.