The MAPPING fitting capabilities are available through the GO UVFIT and GO PLOTFIT procedures and/or the associated widgets (inside the UV interferometric operations widget of the MAPPING menu). These procedures allow you to fit models directly through the visibilities of a table whose filename (without extension) is stored into NAME sic variable. The models are either simple functions or linear combinations of simple functions. The residual visibilities will be written in a table named 'NAME'"-res.uvt". The results (e.g. values of the fitted parameters) will be saved in an output binary file (in detail, a GDF table), named 'NAME'".uvfit". The velocity/frequency channels to be fitted are selected through the FIRST and LAST sic variables.
All other control parameters of the fit and of the plot of the fitted parameters are stored in the UVFIT sic structure
POINT | Point source | X and Y offset, flux |
E_GAUSS | Elliptical Gaussian | X and Y offset, flux, major and minor FWHM, pos. ang. |
C_GAUSS | Circular Gaussian | X and Y offset, flux, FWHM |
C_DISK | Circular disk | X and Y offset, flux, diameter |
E_DISK | Elliptical (inclined) disk | X and Y offset, flux, axes (major and minor), pos. ang. |
RING | Annulus | X and Y offset, flux, inner and outer diameter |
U_RING | *** ? JP *** | X and Y offset, flux, *** ? JP *** |
EXPO | Exponential brightness | X and Y offset, flux, FWHM axis |
POWER-2 | X and Y offset, flux, FWHM axis | |
POWER-3 | X and Y offset, flux, FWHM axis |
The procedures are in fact wrap-up around the UV_FIT task. It uses the public domain SLATEC library which is shipped by default with GILDAS.
The results are stored in a GDF table which can read with the COLUMN command. The table is organized as a matrix. is the number of channels in the input table. The organization along the other axis is as follows P1 P2 P3 Vel A1 A2 A3 Par1 Err1 Par2 Err2 ... A1 A2 A3 Par1 Err1 ... where