The wavelength scales produced in the makee final output spectra are in a polynomial format (see wavelength scale description ) unique to the makee package.

In order to read the wavelength scale with IRAF, you should either convert the 2D spectra into a 1D linear or log-linear spectrum using "combine" or convert to a re-binned 2D linear format using "linear" (and the "-image" option). The former is generally preferred since then only a single rebinning of the data is required, although "combine" does require that the spectra first be normalized to a common flux level. ( Note on IRAF 2D polynomial scales. )

Alternatively, one could use "parsefits" to divide the 2D spectra into 1D spectra for each order. The individual echelle order spectra will have either a "Vista" compatible polynomial wavelength scale (default) or an ASCII "x,y" pair format (using the "-xy" option.)