Relativistic time scales in the solar system
Abstract
This paper deals with a selfconsistent relativistic theory of time scales in the Solar system based on the construction of the hierarchy of dynamically nonrotating harmonic reference systems for a fourdimensional spacetime of general relativity. In our approach barycentric (TB) and terrestrial (TT) times are regarded as the coordinate times of barycentric (BRS) and geocentric (GRS) reference systems, respectively, with an appropriate choice of the units of measurement. This enables us to avoid some of the inconsistencies and ambiguities of the definitions of these scales as these are currently applied. International atomic time (TAI) is shown to be the physical realization of TT on the surface of the Earth. This realization is achieved by a specific procedure to average the readings of atomic clocks distributed over the terrestrial surface, all of them synchronized with respect to TT. Extending TAI beyond the Earth's surface may be performed along a threedimensional hypersurface TT = const. The unit of measurement of TAI coincides with TB and TT units and is equal to the SI second on the surface of the geoid in rotation. Due to the specific choice of the units of measurement the TB scale differs from the TT (TAI) scale only by relativistic nonlinear and periodic terms resulting from the planetary and lunar theories of motion. The proper time τ_{0} of any terrestrial observer coincides with the coordinate time τ of the corresponding topocentric reference system (TRS) evaluated at its origin. τ_{0} is reacted to TT (TAI) by the relativistic transformation involving the GRS velocity of the observer, its height above the geoid and the quadrupole tidal gravitational potential of the external masses. The impact of introducing TB and TT on the units of measurement of length and the basic astronomical constants is discussed.
 Publication:

Celestial Mechanics and Dynamical Astronomy
 Pub Date:
 March 1990
 DOI:
 10.1007/BF00050674
 Bibcode:
 1990CeMDA..48...23B
 Keywords:

 Gravitational Fields;
 Relativistic Theory;
 Solar System;
 SpaceTime Functions;
 Celestial Bodies;
 Computational Astrophysics;
 Earth Surface;
 Equations Of Motion;
 Astrophysics