METHOD

        FIT\METHOD Arg [Parameters ...]

    Select the line profile for fits. Five type of profiles are available.
      - GAUSS     Select gaussian profiles.
        Up to 5 Gaussian, dependent or independent can be fitted in a  spec-
        trum,  according  to  command lines. Variables are Area Velocity and
        Width (FWHM).
      - SHELL     Horn-type profiles for Circumstellar Shells.
        Variables are 1) Area [K.MHz] 2) Center  offset  [in  MHz]  3)  Full
        Width  at  zero level, and 4) Horn-to-center ratio (-1 for parabolic
        optically thick lines, 0 for flat-topped lines,  Infinity  for  per-
        fectly  double peaked lines). Profiles are symmetric. Up to 5 depen-
        dent or independent lines may be fitted. X axis must be frequency.
      - NH3(1,1) or NH3(2,2) or NH3(3,3)
        Compute ammonia line profiles, with the assumptions of gaussian  ve-
        locity distribution and equal excitation temperatures. Variables are
        1) Main group opacity times (  Excitation  temperature  minus  Back-
        ground    temperature),    2)    Velocity,    3)   Width   (FWHM   =
        sqrt(8.0*alog(2.0)) * line 2nd order  moment),  and  4)  Main  group
        opacity.  Up  to  3  independent  lines may be fitted, but it may be
        slow...
      - HFS FileName    for HyperFine Structure
        This is very similar to the NH3 method, but the coefficient  to  de-
        scribe  the  hyperfine structure are read in the file FileName.  The
        first line of this file must contain the number of hyperfine  compo-
        nents (< 40).  The other lines must contain, for each component, the
        velocity offset and the relative intensity. The parameters  are  the
        same as for NH3 method.
      - CONTINUUM       for Continuum drifts.
        Fit  a  single gaussian and a linear baseline at the same time, with
        automatic determination of the parameters. Uses beam-switched infor-
        mation  for  two-component  fitting  if required. The command METHOD
        CONTINUUM accept additional arguments, which can  be  used  to  cus-
        tomize the fit.

    METHOD CONTINUUM [Width [Area_Ratio [Width_Ratio]]]
    where
      -  Width is the width of the beam in arc seconds. By default, Width is
        a free parameter.
      - Area_Ratio is the reference to main beam area ratio, used for  beam-
        switch observing. By default, Area_Ratio is 1.
      -  Width_Ratio  is  the  reference  to main beam width ratio, used for
        beam-switch observing. By default, Width_Ratio is 1.
    A * can be used instead of a numerical value for each parameter, and in-
    dicates that the parameter is free.

    Note that in command LINES, one enters the peak line antenna temperature
    instead of the first variable in the guesses, except for  SHELL  method.
    Command LINES has no effect for CONTINUUM.

    CONTINUUM  and GAUSS methods only are relevant for continuum data, while
    GAUSS, SHELL, NH3 and HFS methods can be used for spectroscopic data.