The graphical user interface is simply called with
If the spectrum is not named spectrum.dat the option -s filename has to be added with filename the name of the file containing the spectrum in the right format (cf. Sect.5.1.1). Two windows will pop up, the main window which contains the input parameters controlling the fit algorithm and the plot procedure and a smaller window that contains a table with line wavelengths and -widths. The parameters displayed in the windows are extracted from the parameter file.
By default (if no parameter file is specified), the program will search for a
parameter file in the following
order: (i) $PWD/fit.inp, (ii) the last one used, as stored
in $HOME/.cora/parameters, (iii) $HOME/.cora/fit.inp which
is a backup of the last one saved, and (iv) compiled-in defaults.
To specify another file, use the command-line option
cora -s spectrum.dat -i parameter_file.
You can also change to another parameter file during the session with File/Open in the GUI.
While the parameter file will be created if it is not present,
provision of a spectrum is mandatory.
By default, the program will expect the spectrum in a file named
spectrum.dat. To specify another file, use the command-line option
cora -s spectrum_file.
If the spectrum cannot be found at startup, you will be informed by a pop up dialog. You can then use the File-Open Data File option to read in a spectrum. Details about the right format are given in Sect. 5.1.1.
The layout of the main window is like a notebook with two folders, the first one holds the fit parameters, and the second one the plot parameters. At the bottom of the GUI there are three buttons:
calls the fit program cora_fit with the current parameter
settings, reads the output and updates the line wavelengths/widths and the
source background sbg with the fitted values. Pressing this button is
equivalent with calling
cora_fit -i parameter_file -s spectrum_file
from the command line (description in next part of this section).
saves the current parameter settings to the
currently active parameter file. This is useful, when e.g. using the GUI in
combination with IDL (cf. Sect. 9).
immediately terminates the application without saving the current settings.
At the top of the window, a 'File' menu provides the following functions:
New Create a new parameter file.
Open Parameter File Open a parameter file.
Open Data File Open a data file
Save Save settings to current parameter file.
Save As Save settings to a new parameter file.
Quit Quit the application.
Next, there is an 'Options' menu for the following options:
Graph Open an interactive X window with a graph of the spectrum.
Go Same as the button.
Remove line Remove a line from the line list (asks for line number)
Replot Last Re-plot the latest computed spectrum without re-computing it.
Replot From File Re-plot the stored computed spectrum without re-computing it.
Create Standard .. Create a standard parameter file.
Set FWHM zero Set all FWHM values except for the first one to zero.
This is implies that all values of FWHM will be the same.
Create TeX file Create a LATEX file from the log-file
ShowLog Show the log window.
Selecting the spectral lines to be fitted can be done in two ways. The lines can be entered directly into the line display window (see next paragraph). First, one has to provide the number of lines which then launches an updated line window with the appropriate number of rows. A more convenient way is to selected from an interactive graphical view of the total spectrum. This is done with Options/Graph. An interactive pgplot environment is launched displaying the total spectrum. Pressing the left mouse button will set left and right borders in order to zoom into smaller parts of the spectrum. Lines are selected with the right mouse button. It is also possible to select a background value pressing the middle mouse button when having the horizontal line running through the cursor position at the desired value of background. Further commands to be used from the keyboard are described on top of the graph. Line widths must be entered by hand in the line display window. If non-positive values are present, all other values will be set to the first positive value. This is useful when dealing with a large number of lines with all the same line widths. Only the first value needs to be set, all others (default zero) will be set to the first value. A GUI option is provided with which all FWHM values can be set to zero, the first value will be kept.