Upper panel: photon indices measured in the 0.5−2 keV (filled circles) and 2−7 keV (open squares) bands for the six intervals of the XMM-Newton observations of PID 203 (X1–X6 in Table 3). The soft-band slopes were obtained by fitting an absorbed power law, while the hard band slopes by a simple power law with a Gaussian for Fe K (Fig. 8). The vertical dashed-line marks the 6-yr gap between the X2 and X3 intervals (see Table 3). Lower panel: absorbing column density (N_H) in excess of the Galactic value measured in the galaxy rest-frame for the six intervals. We obtained these N_H values by using the 0.5−2 keV data. Given the error bars, evidence for variability of N_H is weak with χ² = 6.5 for 5 degrees of freedom.