XMM-Newton (an X-ray telescope) recorded 6 different observations of IGRJ18027-2016. The table below shows the different observation IDs with the different periods, where the period indicates how fast the neutron star is rotating.
The period of the system is important for obtaining the correct folded light curve. Where a wrong period may result in missing or underestimated peeks.
A folded light curve for hard x-ray (2-10 keV) can be seen at the top of figure 2, while the middle graph shows the folded light curve for the soft x-ray (0.2-1keV). The Error bound between the two light curves is seen at the bottom of the graph.