III.8. Calculation accuracy

An ephemeris can be calculated with different accuracy. Calculation accuracy dialog presents three modes of accuracy.

One can calculate position of a minor planet by the formulae of elliptic motion starting from the fundamental set of elements for given minor planet. (Elliptic motion mode). Using the same formulae, one can take instead of fundamental set of elements osculating sets of elements for different moments. These osculating sets are obtained by “interpolation” using values of elements in the nodes of net calculated in advance (Nodes mode).

Also there is possibility to calculate positions taking into account perturbations from different sets of perturbing bodies by numerical integration (Integration mode). The standard set of perturbing bodies includes perturbations from Mercury to Pluto plus perturbations from Ceres, Pallas, and Vesta, but any of the bodies can be excluded. For the Earth – Moon system the perturbations can be accounted by one produced by barycenter or considered separately. Also there is a possibility to neglect relativistic perturbations from the Sun or to include them into calculations.

Coordinates and masses of major planets were adopted from DE405/LE405. To take into account the perturbations from Ceres, Pallas, and Vesta their equations of motion are integrated jointly with those of perturbed minor planet (Their osculating elements and masses are taken from EMP for current year).

The Everhart integration algorithm of the 11th order is used in calculations. Accuracy of integration is equal to 10**(-10) AU. The Integration mode can be used for time interval from 1800 till 2100.

If Integration mode is set in Calculation accuracy dialog, and user excluded perturbations from all planets, then Nodes mode becomes selected automatically.