Top panel: Rotation–activity relationship in the saturation regime for chromospheric data. The green line indicates the saturation value $\log R_{\mathrm{HK}}^{\prime }=-4.10$. The red circles represent the mean $\log R_{\mathrm{HK}}^{\prime }$ in a bin of 0.05 dex. The error bar is the mean error of $\log R_{\mathrm{HK}}^{\prime }$ in a bin. The vertical line indicates the critical Rossby number Ro = 0.022, where the chromospheric activity reaches the saturation. The dotted vertical line indicates Ro = 0.038 where the dichotomy separates the saturated and unsaturated regime. Bottom panel: Same as the top panel but for X-ray data. The vertical line indicates the critical Rossby number Ro = 0.017, where the X-ray activity reaches the saturation.The dotted vertical line indicates Ro = 0.05 where the dichotomy separates the saturated and unsaturated regime.