Top panel: comparison between subsampled collapsed spatial profiles for a selected exposure (left panel) and a rejected one (right panel) for the 2017 September 7 observations of η Ori AaAb+B. Solid black is used for the observed profile, solid red for the fit, and dotted black for the star positions. Bottom panel: same as top panels but for the normalized residual i.e. (observed-fit)/fit. The selected exposure has a more symmetric profile than the rejected one, yielding a much lower χ² and a reduced contamination of the primary on the secondary.