International Astronomical Union (IAU) An international association of astronomers that is the controlling body of world astronomy. It was founded in Brussels in 1919. A general assembly is held every three years, the first one having occurred in 1922. In addition the IAU organizes periodic symposia for the discussion of current astronomical problems, establishes international standards and the official names for astronomical objects, produces several publications, and runs a telegram service for the rapid dispersal of information relating to transient phenomena such as novae and comets. One of the IAU's most important achievements was the establishment in 1929 of official constellation boundaries, making it possible to assign every star and the vast majority of other objects to one constellation and one only.