vbin

 VBIN N1 N2 N3 W0 VP NP METHOD [FRAC] -- Rebins to uniform velocity scale

 The earth's velocity will be removed, or in other words the spectrum is
 rebinned to a heliocentric frame. Edit out Vearth if you don't want this.
 Selection criteria can be applied. The program interpolates bad pixels
 prior to rebinning but masks output pixels if they are more than FRAC
 covered by bad input pixels.

 Parameters: 
     
  N1    -- Slot number of first spectrum to rebin
  N2    -- Slot number of last spectrum to rebin
  N3    -- Slot in which to start results
  W0    -- Central wavelength of region in Angstroms
  VP    -- km/s/pixel
  NP    -- Number of pixels (symmetric about W0)
  METHOD - Interpolation method. Choices:
           L(inear), Q(uadratic), S(inc)

           Quadratic rebinning is recommended for most purposes. Linear
           rebinning is only in case speed is of the essence. Both linear
           and quadratic rebinning cause significant smoothing of the data
           (especially linear). In an effort to reduce this, rebinning using
           a (Sin X)/X = "Sinc" has been implemented. This is much slower, but 
           may be necessary if you are interested in measuring broadening at 
           a level near your spectral resolution for example. The sinc
           function is tapered by a window function to reduce overshoot in
           frequency space. If you do use sinc rebinning, it would be well to
           get rid of cosmic rays and other bad pixels first since their
           effects can spread. A check is made to see if the rebinning 
           requested is really just a shift in which case a fast version
           of sinc interpolation is used.

  FRAC --  (Not prompted for) Minimum fraction of output pixel covered
           by input pixel for it to be masked.

This command belongs to the class: manipulation