Evolution with phase of the hard X-ray flux (top), the absorption (middle) and the normalization factors (bottom) for Cyg OB2 #8A. In the bottom panel, filled and empty symbols represent XMM-Newton and Swift data, respectively. Note that for the middle and bottom panels, all Swift data but those of 00031904005 were grouped to increase signal-to-noise ratio, the length of the bin representing the phase interval covered by the data.