In any experiment, specifying a physical quantity of interest always relies on a reference frame. For example, identifying the time at which an event happens only makes sense relative to a clock.

To execute a movement towards a sensory target, it is necessary to transform the representation of the target from a sensory reference frame (for example, a head-centred reference frame for the ...

VLBI is the only technology that permits determination of positions on Earth with a direct relationship to a celestial reference system. The International Celestial Reference Frame (ICRF) is an ...