Cross-correlation and lag spectra for ObsID 802, 804, 806, and 808. The spectra are shown in the high-energy (20–70 keV) range for highlighting the behaviour around the cyclotron line energies. The brown and blue vertical lines mark the positions of the best-fit Gaussians of the PFS. The vertical grey line mark the spectral best-fit position of the cyclotron absorption line (Doroshenko et al. 2016). Lags are given in phase units.