OK… The coefficients generated by ISIS using the automatic line finding calibration systems and displayed in the GO window (as used in the predefined and file calibration modes) work correctly if entered into the dispersion function accessible from the profile tab to give the correct calibration so at least ISIS is internally consistent. It is still not clear why using these coefficients in Excel for example does not produce the right results though. Perhaps the primary fit that ISIS does is connected with this. The px values in that fit do not appear to be pixel values so perhaps some resampling is done in this preliminary calibration and the final calibration coefficients are calculated relative to this generic fit? (pure speculation on my part though)
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