Comparison between a system in simulation 2 and a system in simulation 4e. Both systems seem to fit the observed positions of the planets, but only the system in simulation 4e is stable for longer than the estimated age of HR 8799. This is an on-sky projection of the simulations assuming a distance of 39.4 pc (van Leeuwen 2007) and inclination 26° (position angle 64° , Matthews et al. 2014). The axis around which the system is inclined is indicated with a dashed line. The position of the star is indicated with an asterisk.