Arcturus synthetic spectra used in the selection of wavelength bins to exclude strong, blended lines. In red the synthetic Arcturus spectrum including only Fe lines. In black the model Arcturus spectra including all line species, except Fe. Top: high-resolution model, R = 47 000. Bottom: low-resolution model, similar to the resolution offered by X-shooter, R = 8800, shown just for comparison. The line selection was done using the high-resolution models.