Combined spectra of Rasalhague. The spectrophotometric part #1401 is shown by the solid black line. Its extension towards the UV is in magenta. The 5% uncertainty of these data is shown by the grey zone around the spectrum. The bandpasses of the filters used in the c′₁ and c₂ indices are shown in red and blue, respectively. The infrared extension is not shown. The green line shows the synthetic spectrum derived from the concordance model given in Table 3. The green zone around this line shows the effect of uncertainties of the rotation axis inclination.