Add Lense-Thirring and De Sitter contributions for relativity
According to IERS 2010 convention, the relativistic correction to the acceleration of an artificial Earth satellite is expressed by the sum of terms:
- Schwarzschild term
- Lense-Thirring term
- de Sitter term
Relativity force model only support Schwarzschild term. However, for precise orbit determination of near-Earth satellite, adding the two other terms can improve the results.
I propose to add two other classes
DeSitterRelativity to implement the two other terms.