Difference of joint ThAr/FP and LFC wavelength solution. Colors indicate different fibers and slices. For better visualization, the sampling of the wavelength solutions is reduced to 100 km s⁻¹. On these scales, the wavelength solutions should anyway be coherent due to the applied smoothing filter. Parts of the extracted traces where the blaze function drops below 25% of the peak throughput are excluded. This also reduces the overlap of neighboring spectral orders. The smoothing kernel utilized to determine D_eff(λ) is visualized in orange.