Results obtained from the analysis of the FORS2 spectra of the velocity standard stars collected from the data of the observations in connection with the entries in Table 2 compared to the reference barycentric LOS velocity values by Soubiran et al. (2018) (also given in Table 2). We plot the estimates of the difference of heliocentric or barycentric LOS velocities against the air mass of the star at the time of observation.