UV_FIT

        [ADVANCED\]UV_FIT  [Func1 .. FuncN]  [/QUIET] [[/SAVE File]
      [/UVRANGE Min Max [Unit]] [/WIDGET N]

    Fit  UV  data  with a few simple functions. Func1 to FuncN (currently N < 5)
    are the names of the functions to be fitted.  If  not  specified,  the  last
    names (or those attributed by the /WIDGET options) are used.

    The  models  are  either  simple  functions or linear combinations of simple
    functions.  Input parameters and results of the fitting process are (in  se-
    quential  order) the position offsets in R.A. and Dec (in arc second) of the
    model source from the phase reference center, and its  flux  (Jansky).   De-
    pending  on  the fitting functions additional parameters and fit results are
    possible. Currently supported distributions and  additional  fit  parameters
    (in order) are:
    POINT     Point source              : None
    E_GAUSS   Elliptic Gaussian source  : FWHM Axes (Major and Minor), Pos Ang
    C_GAUSS   Circular Gaussian source  : FWHM Axis
    C_DISK    Circular Disk             : Diameter
    E_DISK    Elliptical (inclined) Disk: Axis (Major and Minor), Pos Ang
    RING      Annulus                   : Diameter (Inner and Outer)
    EXPO      Exponential brightness    : FWHM Axis
    POWER-2   B = 1/r^2                 : FWHM Axis
    POWER-3   B = 1/r^3                 : FWHM Axis
    U_RING    Unresolved Annulus         : Radius
    E_RING    Inclined Annulus          : Inner, Outer, Pos Ang, Ratio
    E_EXPO    Elliptic exponential       : FWHM Axes (Major and Minor), Pos Ang
    SPERGEL   Spergel brightness profile : FWHM Axis, nu
    E_SPERGEL Elliptic Spergel profile   : FWHM Axes (Maj. and Min.), Pos Ang, n


    The  function parameters are found in a SIC structure named UVF% under names
    UVF%PARi%PAR[7] (starting values), UVF%PARi%RANGE[7] (starting  ranges)  and
    UVF%PARi%START[7] (number of starts). The /WIDGET option is a convenient way
    to set these variables.

    UV_RESIDUAL  will  compute the fit residual when used after UV_FIT, while it
    computes the residual from the Clean component list if used after CLEAN.

    WRITE UV_FIT file[.uvfit] will save the fit results in a  GILDAS  table,  in
    the same format than that of the UV_FIT task.

    The  Pos Ang (PA) are the Position Angles of the major axis of the distribu-
    tion. To deproject the elliptical shapes, one should use the Position  Angle
    of  the  rotational  axis,  PA-90  (see commands UV_CIRCLE, UV_DEPROJECT and
    UV_RADIAL)