Variation in spectral parameters with phase for Obs. 2, including the central energy (E₁,  E₂), width (σ₁,  σ₂), and depth (Depth₁, Depth₂) of the cyclotron absorption line (and its harmonics) and the plasma temperature (kT), plasma optical depth (τ), and normalization (N_comp) of the compTT component. The solid sky-blue line represents the QPO waveform from the Hilbert spectral analysis phase-folding.