Upper panel: joint 68% (dotted) and 99% (solid) confidence contours of the blackbody temperature vs. normalized flux for the hard power-law component. The latter is defined as flux at 1 keV in units of photons cm⁻² keV⁻¹ s⁻¹. Only observations that have good statistics in the spectrum (XMM 2010, Swift 2011, and XMM 2014) are shown. Lower panel: the 2–10 keV flux light curve, which was estimated by fitting a simple model of blackbody plus a weak power-law component. See Section 3.3 for details.