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Determination of the Dispersion Coefficients

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.


Rein Warmels
Mon Jan 22 15:08:15 MET 1996