Variation in spectral parameters with phase for Obs. 1, including the central energy (E₁/E₂), width (σ₁/σ₂), and depth (Depth₁/Depth₂) of the cyclotron absorption line (and its harmonics), the central energy (E_Fe), line width (σ), and normalization (N_gau) of the iron line, and the plasma temperature (kT), plasma optical depth (τ), and normalization (N_comp) of the compTT component. The gray line represents the average profile of the data used for the phase-resolved spectral analysis. The triangles indicate the upper limits.