FC detection limits for PC images of Gl 559A (α Centauri A) through F1042M. This star’s V magnitude is average for the targets in group 3; the detection limits are therefore typical for group 3 targets. All curves and symbols are as described in the legend to Fig. 2 and in § 3.1. The discontinuities in the 10 σ curve at ~1﹩\farcs﹩5 and 3﹩\arcsec﹩ mark the transitions between the 0.11, 30, and 200 s exposure sets.