Two Fe I β Pictoris lines from the ground base level (flux in arbitrary units as a function of wavelength in Å). The observations are shown as black histograms, the fitted stellar continuum as green lines. The blue lines represent the intrinsic absorption feature, and the red lines are its convolution with the HARPS instrumental profile. In the two lines, the intrinsic absorption profiles (blue lines) are far from saturated, implying that the column density of Fe I from the ground base level can be well constrained.