Standards for Terrestrial and Celestial Reference Systems

Abstract

The purpose of this chapter is to review the characteristics of the standards that are required for the specification and use of terrestrial and celestial reference systems. It is clear from the preceding chapters that a wide variety of techniques can be used to determine the positions and velocities of points on the surface of the Earth and of objects in space. The results obtained by different techniques (and by different implementations of one technique, see Chapter 12, Section 2) will differ from each other, but the differences can be reduced by the use of appropriate systems of standards in the derivation of the required results from the observational data. Ideally, there would be a comprehensive, self-consistent system of internationally adopted standards that would be generally applicable, but practical considerations prevent the realisation of such a system. It is therefore usually necessary to use a combination of sub-systems, each of which is appropriate for a limited field of application.