Left: pulse profiles obtained from the merged EPIC data in different energy bands (for better statistics the first two standard energy bands were combined in the top panel, the bottom panel shows all five energy bands combined). The profiles are background-subtracted and normalised to the average count rate (0.116, 0.228, 0.249, 0.207, and 0.801 cts s^-1, from top to bottom. Right: hardness ratios as a function of pulse phase derived from the pulse profiles in two neighbouring standard energy bands.