Evolution of the asymmetry of the CCF during the pulsation cycle of DX Del. The Gaia RV curve for this star is shown in black for global visualisation. The red markers represent the measurements from SOPHIE and the red stars locate three spectra with a high S/N where we can compute the CCF using the three masks with different depths, shown in the inserts. The dashed line shows the mean RV extracted from the Gaia catalogue.