Comparison of the IAG spectral atlas with the Kitt Peak FTS-atlas from Kurucz et al. (1984) and the HARPS atlas from Molaro et al. (2013). Left: three absorption lines around 524.85 nm. To allow comparison to the HARPS atlas, the IAG atlas was artificially broadened using a Gaussian profile and assuming an instrument resolution of R = 110 000. Right: comparison in the wavelength range of Hα. The sharp lines are telluric absorption and mismatch because of different observing conditions. The HARPS atlas does not cover this spectral region.