Sky-plane trajectory and residuals for the absolute-astrometry solution. Top: photocentre trajectory from our joint fit. The black curve comprises proper motion, parallax, and orbital reflex motion. The dashed grey line shows the underlying linear CM motion. Right: residuals. From top to bottom these panels show (I) HIPPARCOS along-scan abscissae, (II) Gaia along-scan abscissae, (III) ground-based positions in α^∗, and (IV) ground-based positions in δ. Bottom: orbital reflex motion of µ Her Aa relative to the barycentre A. We display random draws from the posterior distribution of the absolute-astrometry-only solution in green and the joint solution in black. The pink cone represents the proper motion from the Gaia solution (3 σ uncertainty); the black cones represent the orbital tangent vectors corresponding to the joint solutions.