Published online by Cambridge University Press: 04 August 2017
Fundamental positions and proper motions are derived from absolute catalogs. Taking recent Washington Six-Inch and Seven-Inch Transit observing programs as examples, the observation and compilation of absolute catalogs are discussed. The roles of quasi-absolute and differential catalogs in the formation of fundamental catalogs are also examined. Finally, the current effort to extend the fundamental system to fainter magnitudes than are presently represented in the FK4 is described as well as the expected composition of the forthcoming FK5 catalog.