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Coordinate Systems
| Fundamentals | |
|---|---|
| Title | Coordinate Systems |
| Author(s) | J. Sanz Subirana, JM. Juan Zornoza and M. Hernandez-Pajares, University of Catalunia, Spain. |
| Level | Medium |
| Year of Publication | 2011 |
To describe satellite motion, observables and models it is necessary to have a well-defined and reproducible reference coordinate system. Since the accuracy in satellite systems and the precision requirements are tight, these reference systems have to be accurate as well.
It is important to note the difference between Reference System and Reference Frame, two different concepts. The first one is understood as "a theoretical definition", including models and standards for its implementation. The second one is its ``practical implementation through observations and a set of reference coordinates, e.g. a set of fundamental stars, for a Celestial Reference Frame, or fiducial stations for a Terrestrial Reference Frame.
The ICRS was proposed by the IERS and formally accepted by IAU in 1997. A realization of the ICRS is the ICRF. On the other hand, IERS is in charge of defining, realizing and promoting the ITRS. Realizations of ITRS are the ITRFs, being the ITRF2005 the current reference realization of ITRS.