Left: histograms of the RV biases between the HR21 and the HR10 setups per target. The “GES” and “NACRE” labels refer to RVs as measured by the “VRAD” GES keyword, and as re-computed in this work and in Van der Swaelmen et al. (in prep.), respectively. The bin width of histograms is 0.25 km s⁻¹. Middle: intrinsic uncertainty on the RV (e_int) and physical uncertainty (e_phy) measured on HR10 and HR21 single exposures. Right: RV errors according to Eq. (1) per setup. Middle and right histograms have a bin width of 10 m s⁻¹.