Observed average profiles of pulsar B (black lines), corresponding to the centroids of BP1, BP2, and the IP; the WP profiles were calculated using all the data in that orbital-phase window (see blue error bars in Fig. A.1). Each column corresponds to a different orbital-phase window (labelled along the top edge of the figure); each row corresponds to a different MJD bin (labelled along the right edge of the figure). The grey lines show the lower and upper 1σ_sys confidence limits (Eq. (7)). The blue vertical error bar next to each profile corresponds to the off-pulse RMS, σ_stat, of the average profile.