Observatorio Astron mico Nacional The Observatorio Astron mico Nacional is an institution devoted to research in astronomy. It comprises the Observatorio de Madrid, the Centro Astron mico de Yebes y the Estacion de Observacion de Calar Alto. It was founded in 1790, and currently it is part of the Instituto Geografico Nacional (Ministerio de Fomento). OAN sites Description of all sites that are ...