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Refers to a reference system centered at some location on the Earth (for example, the geographic location of an observatory). The topocentric distance to an object is the distance between the object and the topocenter (for example, the observer).
The list of defined terms to the left is by no means exhaustive with
respect to the general subject of solar system dynamics.
The terms listed are thought to be those more commonly used on our site
and thus appropriate for inclusion on this page.