Left: inclination vs. simulated excess noise for BD+192536. The red lines mark the value of for this star ± 10%. Top-right: example of a simulation of Gaia measurements (blue points) for the peculiar case of BD+192536 that fits the value of ϵ_DR1 = 1.02 mas. The true proper motion and true parallax are assumed to be subtracted. The purple line is the residual proper motion (moving centroid) fitted to the simulated measurements and the red cross marks the true centre of gravity of the system. Bottom-right: residuals with respect to the moving centroid.