Post-fit residuals on the (AL, AC) plane for (105) Artemis (top row), (25) Phocaea (middle), and (176) Iduna (bottom row). The error bars represent the 1-sigma level of the uncertainties assigned by the error model. In the right panel, they have been normalised to the apparent average radius of the asteroid at the epoch corresponding to each observation. The corresponding circle is shown. The red crosses represent observations that are rejected by the orbital fitting process. Larger symbols are used for events with >2 chords. The plots for (105) are compared to Fig. 7 in Spoto et al. (2017).