[ADVANCED\]UV_FIT [Func1 .. FuncN] [/QUIET] [/SAVE File] [/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 ref-
erence center, and its flux (Jansky). Depending on the fitting func-
tions additional fit results are possible. Currently supported distribu-
tions and additional 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
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 dis-
tribution. To deproject the elliptical shapes, one should use the Posi-
tion Angle of the rotational axis, PA-90 (see commands UV_CIRCLE, UV_DE-
PROJECT and UV_RADIAL)
Subsections
Gildas manager
2023-06-01