Radial velocity curves of δ Cep without correction from the presence of the companion. Left: comparison of the high-quality cross-correlated radial velocity curves, RV_cc-g (Gaussian fit of the cross-correlated function), of δ Cep available in the literature. These data are not corrected for the center-of-mass velocity variation due to the inner companion, which explains the dispersion obtained in the curves. The data studied in this work are shown with blue triangles. For comparison, the pulsation template provided by Hocdé et al. (2023) (green curve) has been shifted by the γ velocity of −16.95 km s⁻¹ found by Nardetto et al. (2017). Middle: radial velocity curve from the left panel compared to the pulsation template. Right: same as the middle panel but as a function of the BJD. The long-term velocity variation due to the companion is clearly seen.