Results of the timing checks that were performed based on the literature. The pulse profiles were obtained using the timing solutions published in Lin et al. (2013, top) and Wang et al. (2018, bottom). Both Fermi-LAT and XMM-Newton counts were normalised to 1. Statistical error bars are included for both phaseograms. The dotted vertical lines indicate the best-fit locations of the X-ray peak and higher γ-ray peak. No photon weights were applied.