Distribution of σ[υ_rad,Nacre] with (red line) or without (filled black area) a cut on the S/N (binwidth = 0.016 km s⁻¹). Left: HR10 setup; 〈σ[υ_rad,Nacre]〉 = 0.39 km s⁻¹ with S/N ≥ 3. Right: HR21 setup; 〈σ[υ_rad,Nacre]〉 = 0.40 km s⁻¹ with S/N ≥ 3. With or without the S/N cut, most of our sample is characterised by a standard deviation on the radial velocities measured from the different NACRE CCFs below 1 km s⁻¹; the S/N cut depopulates the right tail of the HR10 distribution.