Upper panel: S_MW index variation of ζ¹ Ret. HARPS data are indicated with blue circles (for both panels), while REOSC and FEROS data are indicated with green triangles and orange squares, respectively. Lower panel: activity variation for ζ² Ret. Here, UVES data are indicated with black diamonds. Both vertical dashed lines in each panel represent the time coverage of those series that were initially reported, while the new data are indicated with red crosses. Red and black dashed lines show the fitted activity maxima f(t) for both peaks.