Example of wavelength transformation correction. The red vertical lines mark the strong sky lines with high typical peak intensities from an atlas of optical sky emission (see details in the text). The x-axis represents the wavelength, while the y-axis represents the intensity in arbitrary units. In this example, three sky lines are identified (λ = 6533.05, 6553.63, 6562.76 Å). After correcting the wavelength transformation, the observed sky lines align correctly with the wavelengths from the atlas.