Coordinate independence of physical observables in the classical tests of general relativity

The coordinate-dependence or independence of various quantities in the physical processes of the classical tests of general relativity is investigated by solving the differential equations for the orbits in the post-post-Newtonian approximation. It is shown that the predictions of the physical observables, such as the perihelion advance, the deflection of light ray and the time delay of radar signals are independent of the choice of the coordinate systems. This is clarified by expressing the observables in terms of the constant of motion, namely, the energy of the system, the angular momentum and the impact parameter