National Astronomical Observatory (Mexico)

National Astronomical Observatory (Mexico)

Dome of the 2.1 m telescope on San Pedro Mártir
Organization	National Autonomous University of Mexico
Location	Sierra San Pedro Mártir, Baja California state, Northwestern Mexico.
Coordinates	31°02′38″N 115°27′49″W / 31.0439°N 115.4637°W / 31.0439; -115.4637Coordinates: 31°02′38″N 115°27′49″W / 31.0439°N 115.4637°W / 31.0439; -115.4637
Altitude	2,800 meters (9,200 ft)
Established	1878 (1878)
Website	OAN SPM
Telescopes
unnamed telescope 2.1 m reflector unnamed telescope 1.5 m reflector unnamed telescope 0.8 m reflector
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The National Astronomical Observatory (Spanish: El Observatorio Astronómico Nacional—OAN), the national observatory complex of Mexico, in Baja California state.

The observatory was first established on the balcony of Chapultepec Castle in Mexico City in 1878. The observatory has been operated by the National Autonomous University of Mexico (UNAM) since 1929.

It was later moved to Palacio del Ex-Arzobispado in Tacubaya, then on the outskirts of the city on the west side of the Federal District. The location is remembered by the name Metro Observatorio, the terminal station of the Line 1 of the Mexico City Metro located nearby.

In the middle of the 20th century, OAN had to move from the increasingly crowded and polluted Valley of Mexico, to Tonantzintla in Puebla state, Central Mexico.

In 1967 excessive air pollution and night light pollution caused another move, from Puebla to atop the Sierra San Pedro Mártir mountain range of Baja California state in Northwestern Mexico. The San Pedro Mártir OAN site has been found to have excellent astronomical seeing.

There are three optical telescopes on the summit of the Sierra San Pedro Mártir at the OAN complex, all with a Ritchey-Chrétien design: