Distribution of measured wavelength corrections υ_shift in km s⁻¹, for each grating (dark blue). We indicate the mean R136 velocity of 267.7 km s⁻¹ as measured by Hénault-Brunet et al. (2012, black dashed lines), together with the non-binary-corrected velocity dispersion of σ = ±25 km s⁻¹ (orange-red shaded), as well as a velocity range corresponding ±2 pixels around the R136 mean (yellow shaded). The numbers in the upper right corner of each plot denote the amount of stars that fall out of the plotted velocity range. Below that, we show the inferred mean µ, median M and standard deviation σ of each grating (all in km s⁻¹).