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The initial screen of the line ID GUI (based on x_identify from xidl) is shown below:
This screen shows a view of the order-center arc trace, with the x-axis as pixel number. The first-round line identifications are indicated in red based on the cross-correlation procedure.
The x_identify GUI is fairly complicated (and occasionally buggy) but only a few commands are relevant for our purposes. At any time, you can type a capital 'H' to get a summary of key commands. Here are the most important ones for this screen:
- Zooming in / out: To zoom in and out in the spectrum, center the cursor over the region of interest and type 'i' for in or 'o' for out. Alternatively, you can redefine the top/bottom/right/left of the view port by positioning the cursor and typing 't', 'b', 'r', or 'l', respectively. To zoom restore the original zoom parameters type capital 'W'.
- Adding a line: First, make sure the correct line list is highlighted. This should be NeAr_fire2.lst and must be included in your $XIDL_DIR/Spec/Arcs/Lists directory to work properly (if you don't have this file the GUI wil probably crash at startup...). Then, center the mouse over an emission feature in the spectrum and left-click. This will launch a pop-up window that allows you to specify which wavelength should be associated with this line.
- Line ID key: A postscript plot showing the line IDs we feel give a good solution can be found here. Note that many more lines exist in the spectrum, but in some cases these do not help the quality of fit because of blending, etc.
- Deleting a line: Hold the cursor near the "x" that marks the offending line, and press capital "D".
