Variation of the count rates and hardness ratio with orbital phase, for XMM-Newton (in black dots), Chandra (filled black triangle), and Swift data (empty red triangles for 2013, empty green squares for 2014, and empty blue pentagons for 2015). For all energy bands, Chandra and Swift count rates and their errors were multiplied by 5.4 and 19, respectively, to clarify the trends, and no further treatment was made for adjustment. To help compare with physical parameters, the bottom left panels provide the orbital separation (in units of the semimajor axis a) as well as a position angle defined as zero when the WR star is in front and 180° when the O-star is in front. The vertical dotted lines in the left panels thus correspond to the quadratures and the other dotted line to an arbitrary 1 /D variation (not fitted to the data); periastron occurs at φ = 0.0.