Polar periodogram for the 2011 and 2012 HD 128621 datasets after YARARA correction. For 2012, the highest peaks in the periodogram correspond to a period of 40 days, so we display the polar periodogram at 40 days rather than36 days. A clear time-lag between the RV variation of each line and the CaII H&K (purple cross) of ϕ ~ 90° (9 days) and ϕ ~ 45° (5 days) is visible in 2011 and 2012, respectively. The RVs are however in phase with the multi-linear model of α_j (pink square) as well as with the CCF FWHM (orange star).