Relativistic celestial mechanics at sub-microarcsecond accuracy level
Authors: Biswas Abhijit , Mani Krishnan R. S. 
Published: October 2019

Einstein stated two dictums, so that more experimental facts can replace the previously adopted hypotheses and General Relativity (GR) can evolve to “grand aim” or perfection. In the absence of appropriate experimental facts during pre-CEREPAC (Century-long Experience
of Relativity-related Experiments on Physics, Astronomy and Celestial-mechanics) era, Einstein found no “escape” from the consequence of non-Euclidean geometry, while keeping all frames permissible based on contemporary knowledge. Bergmann also
stated in 1968 that the “principle of general covariance” has brought about serious complication in GR. During CEREPAC, relativists and mathematical-astronomers invariably identified the appropriate “nature’s preferred-frame,” which was later found essential for
operation of conservation laws. Based on CEREPAC, replacing the experimentally unverifiable hypotheses with experimentally proven principles, and improving upon the GR-astronomers model (developed by JPL, USA, as an evolved-version of GR-conventional model) in two successive stages, GR was
remodeled to what became evident as Evolved GR (EGR), after it enabled the elimination of all earlier-adopted ad-hoc methods or approaches, and of the problems, paradoxes and anomalies, associated with the applications of GR, during CEREPAC, and after it unraveled the “General-relativistic
nature of speed-of-light (c)” which links the variable c r with F r, the local Gravitational Red-Shift Factor (as stated by Einstein between 1911‐1921). As a consequence of the space-age developments in numerical simulation and in the availability
of precision observational data, it got proven that nature itself operates the conservation laws of energy, and of linear and angular momentums (both magnitudes and directions), with respect to the appropriate “nature’s preferred frame”; this provided sufficient reason for
giving up the “relativity of all frames,” bringing back Euclidean geometry in EGR. Euclidean space in EGR enabled development of a Prototype of future Ephemerides, leading to five orders-of-magnitude improvement in accuracy of computation of precession of celestial orbits, using
three independent methods; this methodology of Prototype Ephemeris and “three-methods-match” can also be applied while remaining exclusively within the precincts of GR, by using one alternative mode of running the EGR program for planetary and Lunar orbits,
by opting for GRTOPT=Y; this mode utilizes exclusively the GR equations instead of EGR equations; in fact, this mode is the GR-astronomers (modified) model that was really an intermediate stage of evolution (as mentioned above) between the GR-astronomers model and the EGR model. This
model incorporates: (1) All good (and, experimentally proven) features from the three generations of GR models (Einstein’s original, Bergmann’s and Misner-Thorne-Wheeler or MTW), and (2) The “Nature-adopted” real orbital model (as proven from comparison
of the computed precession values at Micro-arcsecond {μas} level using the “three-methods-match”) for its Methodology for Conservation of Linear and Orbital Angular Momentums, in a polar coordinate system (r, , Φ). This model computes: (1) Precession of celestial
orbits at nearly the same accuracy as that done using the EGR model, and (2) About three digit more accurate (than reported by Folkner in 2014, from fitting lunar laser ranging data with an updated lunar gravity field from the GRAIL mission, etc.) orbits of inner planets and the Moon.