Left panel: pulse profiles extracted from all the observations in Table 1 as a function of energy. Red (blue) colors indicate higher (lower) count rates at different pulse phases and energies. As discussed in Sect. 3.1, the higher intensity is around phase  ~0.3, in correspondence with the “main peak”. The pulse profiles in this figure were all scaled to have in each energy bin a zero average value and a unitary standard deviation. Right panel: values of the correlation parameter C_e, as a function of phase lag with respect to the reference pulse profile and energy. Red (blue) colors indicate values of C_e close to unity ( ≪ 1). See text for details.