EPiCA profiles DRV(i) along the velocity grid for pairs of time periods (lines with markers). Offsets of 30 m s⁻¹ are applied between two consecutive profiles, except for the two top curves, which are plotted together. The actual zero value is indicated by a black thin line. The size of the markers is increasing with the individual weight for each series. A typical weight function is also plotted (thin dot-dashed line). The two most central values suffer from additional uncertainties due to the limited velocity sampling and are delimited by a rectangle. (Top curves) For pairs made of the second to fourth parts of night 24, the profiles are flat within the error bars, showing no significant change in shape; this is consistent with the constancy observed using ratios, pointing to a stabilization of the instrument. For each of the other pairs (lower curves) containing the first and second parts of a night, one can observe departures from a flat profile, and a similar shape with an amplitude increasing from night 24 to night 28. This typical shape of DRV(i) is induced by a decrease in contrast (see text), consistent with the same type of behavior as the bump measured using CCF ratios (Fig. 12). It could be due to a stellar process or to an artifact.