Line core shift of Fe I spectral lines, estimated using the recalibrated wavelengths λ_nist as reference laboratory wavelengths, measured on HARPS-LFC Moon spectra in the blue chip (blue dots) and in the red chip (red dots). Line core shifts of the two Fe II lines are displayed as orange symbols. Blue, red, and black dashed-dotted lines show the linear fits of the blue, red, and all dots corresponding to the lines with EWs smaller then 170 mÅ. The horizontal black dashed line shows the theoretical solar gravitational redshift (GRS) measured on Earth, v_GRS, theo = 633.10 m s⁻¹. The green dashed-dotted line shows the mean line core shift, v_GRS, obs, of the N = 15 lines at EWs greater than 150 mÅ. The light blue and light yellow regions show the standard deviation, σ_GRS, obs, and the .