Radial velocities of HD 123351. a) Phased STELLA radial velocities with the orbital period of 147.8919 d. Dots are the observations and the line is the orbital fit to the spot-corrected elements in Table 2. b) Top panel: the four years of monitoring. Such data sampling is made possible with robotic telescopes. The line is again the orbital solution from Table 2 (column “Spot corrected”). Lower panel: residuals after removal of the orbital fit. The modulation is due to stellar rotation and the insert shows a DFT periodogram with the strongest peak at 61.0  ±  1.1 d, in agreement with the photometric period. The full amplitude varied over the years between 400 m s^-1 in 2007 and 100 m s^-1 in 2009, indicating the variable asymmetry of the spot distribution. The line is a Blackman-function fit to the data.