Variation for the Fe i λ6705 line in HD 50890 of the fit quality (colour-coded as a function of ) for different combinations of vsini and ζ_RT. The best fit is found for ζ_RT = 11.1 and vsini = 10.6 km s^-1 (and [Fe/H] = +0.05). Similar results are obtained for Fe i λ6703. Note that the fit quality of the analysis that made use of a calibrated ζ_RT of 7.6 km s^-1 (and which led to vsini = 12.5 km s^-1) cannot be judged from this figure because the adopted metallicity is different.