Dependence of Δv_pair on wavelength when our empirical IPs are used (top panel) and when Gaussian IPs are used (bottom panel). Small grey dots are the 1472 Δv_pair values and large black dots with error bars are the means and the standard deviations calculated over binned values. Bin edges were determined such that a single bin contain all astrocomb lines appearing in the same echelle order. In calculating the above quantities, we ignored values falling outside of ±20 m s⁻¹ (±50 m s⁻¹) for the empirical (Gaussian) IP cases. The red line in each panel is the best-fit straight line going through the binned values (see text for parameter values). The red hashed histogram and the red labels on the right spine of the figure show the number of grey dots falling in each bin. The bin at λ = 687 nm contains a single point.