Table 2
Initial parameters of Neptune used in the dynamical model.
| Parameter | Model value | Uncertainty and Ref. |
|---|---|---|
| x(t0)[a] | Values from NEP081 | |
| GM(System) (km3 s−2)[a] | 6 836 527.100580397 | 10 (Jacobson 2009) |
| GM(Triton) (km3 s−2) | 1427.598140725034 | 1.9 (Jacobson 2009) |
| J2(10−6)(a) | 3408.428530717952 | 4.5 (Jacobson 2009) |
| J4(10−6)(a) | −33.398917590066 | 2.9 (Jacobson 2009) |
| ∆ J2(10−6) | 4.564428385417 | |
| ∆ J4(10−6) | −73.851379884207 | |
| GM (Sun and other planets) | Sun and Jupiter, Saturn, Uranus system | Values from DE440 (Park et al. 2021) |
Notes. The initial date of Triton's orbit integration is set to t0 = 2 447 763.5 (TDB), on August 25, 1989, which meets the moment of Voyager’s encounter. The GM (System) is for the Neptunian system and the reference radius for Neptune is 25 225 km. The values of J2 and J4 are the Neptunian second and fourth zonal harmonics of the gravitational potential. The perturbations from inner satellites (Naiad, Thalassa, Despina, Galatea, Larissa, Proteus, and Hippocamp) were considered by adding corrections to J2 and J4, ∆ J2 and ∆ J4 for Neptune respectively. Gravitational effects of the inner planets are taken into account by augmenting the solar mass with their mass. [a] is the parameter to be determined. They are adjusted in our orbit fitting process, with the results provided in Table 3.
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