Upper panel: our radial velocity measurements for HD 116458 are plotted together with those of Dworetsky (1982) against orbital phase. The solid curve corresponds to the orbital solution given in Table 12. The time T₀ of periastron passage is adopted as phase origin. Bottom panel: plot of the differences O−C between the observed values of the radial velocity and the predicted values computed from the orbital solution. The dotted lines correspond to ± 1 rms deviation of the observational data about the orbital solution (dashed line). Open triangles represent the data from Dworetsky and open squares our CASPEC observations; all other symbols refer to our high-resolution spectra obtained with various instrumental configurations, as indicated in Table 3.