The command CALIBRATE/LONG determines the dispersion relation
for each row of the spectrum. In addition, a bivariate dispersion
relation is computed if the keyword is set to
YES, as in:
Midas...> SET/LONG TWODOPT=YES
Midas...> CALIBRATE/LONG
The command CALIBRATE/LONG determines row-by-row polynomial solutions of degree stored in the table coerbr.tbl and fits a 2-D polynomial of degree to the lines with entries in columns :X, :Y, and :WAVE of table line.tbl. The coefficients of the 2D polynomial are stored in the keyword . The program performs a final oulier rejection which eliminates all lines with residuals larger than pixels (if TOL is positive). However the minimum number of lines in any given row will be +2. If this number cannot be obtained, a polynomial of lower order will be fitted. Three more columns are added to the table line.tbl:
Note a proper calibration, images should preferably have positive step descriptors and the wavelength should increase from left to right.