Optimized spectroscopic solution for the RVs of the primary component of ExtEV. The points on all panels are marked with different colors depending on the spectrograph (labeled in the top panel). The blue curve represents the best-fit model. (a) RV curve including orbital solution and the long-term changes. (b) RV curve with the orbital solution subtracted. (c) RVs phased with the orbital period given in Table 6 after freeing from the long-term changes of RVs shown in panel b.