Left: residual’s histogram of the HD 202730 observation shown in Fig. C.7 and the best Gaussian fit to it. Right: the two-dimensional distribution of the relative secondary’s position in the sky for 10 000 Monte Carlo simulations is shown in grey-shading. Contour lines indicate 1, 2, 3-σ confidence intervals. The blue line indicates the position angle of the binary, the red circles show the equivalent u-v-coordinates of the observations, and the solid red line illustrates the average projected baseline orientation.