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.   The  results of the fitting process are the position offsets in
    R.A. and Dec (in arc second) of the model source from  the  phase  reference
    center,  and  its  flux  (Jansky).  Depending on the fitting functions addi-
    tional fit results are possible. Currently supported distributions and addi-
    tional fit parameters 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)