Coplanarity test for HR8799bcde. The scatter plot illustrates the vector coordinates on the sky plane (see text) for the HR8799b (blue), HR8799c (red), HR8799d (orange) and HR8799e (green) allowable orbits. All the points on a given circle refer to orbits characterized by the same inclination. Similarly, all points on a given radial branch refer to orbits characterized by the same longitude of the ascending node. The angle between two spokes corresponds to 20°. The solid lines represent the 68% confidence interval around the most probable vector coordinates, which are depicted by thick points.