MAKPLAN

     MAKPLAN

     This task creates double-beam maps of ON-THE-FLY scans for RESTORE.
     It uses the position variable SCAN_COORD to resample the data variable
     SIGNAL on an azimuth-elevation grid G. The data is gridded line by line
     (subscan by subscan), apodized in azimuth to the frequency cutoff of the
     telescope using the envelope of a sinc function tapered over a gliding
     window F, weighted according to the inverse density factor W required to
     obtain uniform data sampling and, finally, written to a file with the
     extension .mdb. The size of the gliding window is chosen to be 5x the
     beamwidth at the effective observing frequency. The weighting factor W
     is introduced to control the form of the beam, and its value is related
     to the area density of the data at any point j in the new grid:

                           --
                      Wj = \    sin (uj)/(uj).Tj
                           /
                           -- F

                  uj = A .pi.D/lambda.(j-SCAN_COORD)

     where T is an optional apodization function and A is the ratio of
     the halfpower width of the gridding function W to the beamwidth of
     the telescope. T can either be truncated-gaussian (by default),
     parabolic, linear or equal to unity (no taper). So far, the i-th
     point of a specific line in the double-beam map G can be written to:

                           --
                 Gi = 1/Wi.\ SIGNAL.sin (uj)/(uj).Tj
                           /
                           -- F

     Apodization in elevation is done according to the setting of the
     logical SMOOTH_EL. The grid cells are by default quadratic and
     their size is set either to the sampling interval in azimuth or in
     elevation, whichever is larger. However, different sizes in both
     directions can be set using variable MAP_CELL. Flagged channels
     are not reduced.