Differences in Triton and Nereid orbits between the model including complete perturbations from all the inner regular satellites of Neptune and other simplified models. The complete perturbations from inner regulars are calculated by using the positions provided by NEP090 ephemerides (Brozović et al. 2020). Parameters and are the corrections applied to the coefficients J₂ and J₄, respectively,for the simplification and speeding up of calculations of perturbations from inner regular satellites. The initial epoch is always 1989 September 1 TDB, near the time at which the most accurate data are obtained during Voyager’s encounter. The red area is the period spanned by Voyager encounter data (1988–1989) and the gray area without such data (1847–1987 and 1990–2020).