Results obtained when the time-resolved XMM-Newton data alone are fitted with a simple absorbed power-law model. From the top to the bottom panel we show the absorption column density, the power-law photon index, and its normalization. As discussed in the text, it is evident that the most prominent spectral changes took place during the second flare (the first one being much fainter than the other two and occurring in this figure at approximately t = 500 s). The uncertainties on the x axis correspond to the integration times of the spectra 1−20 in Fig. 2.