Joint AL-AC post-fit residual distribution of the reference stars in the last 10 transits of the GAREQ field (further described in the main text) surrounding the target star and showing σ_AL = 162 μas and σ_AC = 1.469 mas, which is depicted as the red shaded ellipse in the form of the 1-σ joint uncertainty. The corresponding AL and AC histogram residual distributions are shown in the margins.