Excerpt of CCF sequence corresponding to time range between Julian date (JD) 2 456 432 and JD 2 456 607 (compared with light curve of μ Cep on bottom panel of Fig. 3). The last three JD digits are listed on the top of each subpanel. Colors correspond to different masks, mask C1 probes the innermost atmospheric layer while mask C5 probes the outermost layer. Vertical lines at 21.4 km s⁻¹ indicate the mean radial velocity, computed from all masks and epochs (see text).