Pole orientation of Neptune difference between the model including the perturbations from all inner regulars and that including the perturbations from only one inner regular, Proteus. All perturbations from inner regulars are calculated by using the positions provided by NEP090 ephemerides (Brozović et al. 2020). The initialepoch is 1989 September 1 TDB. The pole orientation difference is shown in the right ascension (α_p) and declination (δ_p) referred to the ICRS.