The Observatorio Astronómico Nacional

For a historical overview from the origins of the Observatory to the research work carried out these days, we recommend this article in Spanish by Rafael Bachiller, Director of the OAN.


The research work of the OAN is structured in six well-defined areas that are addressed mainly through observations in radio astronomy:

  • Star formation.

  • Astrochemistry.

  • Interstellar medium.

  • Evolved stars.

  • External galaxies.

  • Very long baseline interferometry.

In order to develop these works, we use radio telescopes at different locations on the planet: the 40-meter radio telescope of the Yebes Observatory (Guadalajara) and the interferometry networks in which it is involved (for instance, the European VLBI Network, EVN); the 30-meter radio telescope located in Pico Veleta (Granada) and the NOEMA interferometer in the Plateau de Bure, in the French Alps, both belonging to IRAM; and the ALMA interferometer located in the Atacama desert (Chile).

The OAN, through the Instituto Geográfico Nacional, has participated in the creation and operation of international astronomical institutions such as the Institute of Millimeter Radio Astronomy (IRAM), a cooperation of Spain, France, and Germany, or the European Consortium for Very Long Baseline Interferometry (EVN/JIVE), which involves some of the most advanced scientific research and technological developments in the field of astronomy as well as its applications to geodesy.


The OAN makes a great investment of personnel and resources in the conservation and promotion of its valuable architectural heritage and historical instrumentation at the Royal Observatory of Madrid. The oldest of its buildings, the "Villanueva", one of the most interesting exponents of Spanish neoclassical architecture, was declared an Asset of Cultural Interest (Bien de Interés Cultural), in the category of Monument, by Royal Decree 764/1995, of May 5. Since 2021, the Royal Observatory of Madrid is part of the UNESCO World Heritage within the so-called "Landscape of Light", which covers the Prado-Retiro axis. This way, UNESCO has recognized the relevance of bringing together, in an urban environment, nature, culture and science from the mid-sixteenth century to the present day. The Royal Observatory represents the value assigned to scientific disciplines in the 18th century during the reign of Carlos III.

As part of the effort for the conservation and promotion of the heritage, we built a spectacular replica of the 25-foot telescope, manufactured in 1796-98 by one of the greatest astronomers of all times, William Herschel (1738-1822); it was one of the largest telescopes in the world at that time. Also noteworthy is the construction and installation of the Sala de Ciencias de la Tierra y del Universo, a little museum that displays the valuable collection of old instruments of the Observatory and the whole IGN.

The Royal Observatory of Madrid also treasures an important bibliographic heritage in its library. In this link you can consult the catalog of the works included in the Spanish Collective Catalog of Bibliographic Heritage (CCPB). To restrict the search to our library, select Madrid > Madrid > Real Observatorio de Madrid from the drop-down menu "Consultar el catálogo de".

The historical documentary archive of the Real Observatorio de Madrid can also be consulted in digital format at this link. It contains historical documents related to the Observatory from 1843 to 1965, with documentary series including correspondence, log books, and solar eclipse records, among others.


A bird's eye view of the Real Observatorio de Madrid.


The RTVE programme "The Pillars of Time" shows a 3D scan of the emblematic Villanueva building.


Infographic by Daniel Montero Galán on the Real Observatorio de Madrid (eme21mag magazine)."



The OAN is entrusted with the task of calculating ephemerides, that is, the time and visibility of astronomical events such as sunrises and sunsets, eclipses, conjunctions, etc., and it is the institution responsible for providing official information on astronomy at the national level. It produces the official certificates that may be required for experts’ reports (e.g. in a trial). It provides information on astronomical events for the general public both on this website and in its prestigious almanac (Anuario del Observatorio Astronómico de Madrid).

The Anuario del Observatorio Astronómico de Madrid has been published since 1860. Its main objective is to provide official information on astronomy and to intensify the popularization of this science. It lists the ephemerides, includes explanations on how to use them, brief catalogs of stars of interest to the amateur astronomer and various outreach articles.


In addition to promoting the heritage of the Royal Observatory, the scientific staff of the OAN regularly gives lectures on astronomy, both inside and outside its premises, and publishes articles of this nature in books and magazines published by the OAN and others. A strong effort is also made to disseminate information and news about astronomy in the media.