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Line Identification

In order to compute the dispersion relation, lines stored in table line.tbl have to be cross-identified with a reference catalogue \fbox{LINCAT}. For the first few spectral lines in the central row, this has to be done interactively, the rest is automatic. The sequence:

Midas...> SET/LONG LINCAT=hear.tbl
Midas...> IDENTIFY/LONG

plots the central row of the comparison spectrum \fbox{WLC} on the graphics device and activates the graphic cursor. The lines are selected by positioning the graphics cursor on them and clicking the left-hand mouse button or Return. On the session terminal you will be prompted for the wavelength (to be entered in the same unit as in \fbox{LINCAT}). The command will search for a corresponding entry in table line.tbl. If it is found, the wavelength you enter interactively will be stored in the column :IDENT of table line.tbl. An asterisk, `` * '', will delete a previously made identification. To exit, click the middle mouse button on the graphics device.

At least 2 lines have to be identified interactively, but it is safer to identify a few more, especially if the dispersion relation is sensibly non-linear. They should be evenly distributed over the relevant range in wavelength. The identifications can be checked with:

Midas...> PLOT/IDENT

which plots the central row of the comparison spectrum and the interactive line identifications.


next up previous contents
Next: Determination of the Dispersion Up: Getting the Dispersion Solution Previous: Line Detection in the
Petra Nass
1999-06-15