Absolute convective blueshift of Fe i lines measured from the IAG atlas. Left: blueshift measurements for individual lines (gray points) as a function of line depth. The measurements are corrected for gravitational redshift of 636 m s^-1. The median of the blueshift measurements is shown in bins of size 0.05; the error bars show the standard deviation for each bin. A third-order polynomial (Eq. (2)) is fit to the binned data. Right: blueshift measurements as a function of line equivalent width as measured by Allende Prieto & Garcia Lopez (1998).