Left: random selection of 200 orbital solutions from the converged part of the MCMC chain. The dashed green and dash-dotted orange ellipses represent the highest-likelihood model from the MCMC chain and the lowest χ² orbit from the least squares fit, respectively. The blue star marks the location of GG Tau Aa, whereas the dotted ellipse traces the continuum peak intensity along the ring (Andrews et al. 2014; Dutrey et al. 2014). Right: zoom on the region with astrometric coverage. Blue and red points indicate previously published and new astrometric measurements, respectively. The same orbits as in the left panel are rendered.