Panel a: flare lightcurve (black, solid) and fit to exponential decay (red, dashed). The green, dotted curve shows the exponential-decay component of the combined fit of exponentially decaying QPP and exponential decay (“full-flare exponential” fit), while the blue dot-dashed curve shows the exponential-decay component of the combined fit of Gaussian-decaying QPP and exponential decay (“full-flare Gaussian” fit). The data are from the entire 0.2–12 keV range. The blue and green curves are almost identical and, therefore, difficult to distinguish. Panel b: detrended flare lightcurve (black, solid). Detrending was performed by subtracting the exponential decay fit plotted in panel a from flare lightcurve also plotted in panel a. The red, dashed curve shows an exponential decaying sinusoid, while the blue, dot-dashed curve shows a Gaussian decay in the sinusoid, both of which were fitted to the detrended flare lightcurve. The blue and red curves are almost identical and, therefore, difficult to distinguish. Panel c: flare lightcurve (black, solid) and fits to lightcurve consisting of the sum of exponential decay term and decaying sinusoid. The red, dashed line shows the fit when the decay of the sinusoid was described by an exponential, while the blue, dot-dashed curved shows the fit when the decay of the sinusoid was described by a Gaussian. The blue and red curves are almost identical and, therefore, difficult to distinguish. Panel d: autocorrelation of detrended lightcurve (black solid line) from panel b. An exponentially decaying lightcurve was fitted to the autocorrelation (red, dashed line).