Stargazing at San Pedro Mártir: can you visit Mexico's national observatory?

Stargazing at Sierra de San Pedro Mártir in Baja California takes you near Mexico’s Observatorio Astronómico Nacional (OAN-SPM), run by UNAM at about 2,800 m. You can visit the observatory by day for free, but you can’t look through its 2.1 m research telescope; the night sky is yours from the national park outside.

What is the San Pedro Mártir observatory?

UNAM’s national astronomical observatory in the Sierra de San Pedro Mártir, with a 2.1 m telescope as its main instrument. The site’s height above most of the atmosphere is the reason it is there.

How do you visit OAN-SPM?

• Hours: UNAM lists 10:00 to 13:00 and 14:00 to 15:00.
• Cost: free, no reservation, subject to permission from the head of operations.
• Closed: the last two weeks of December and the first week of January.
• Limits: entry inside a telescope is not guaranteed and observing through it is not allowed.
• Park fee: the national park entrance fee does not include the observatory.

How to prepare for stargazing at San Pedro Mártir

At about 2,800 m, nights are cold and the air is thin; bring winter layers and water. The road is long and services are few, so fill the tank, download offline maps, and tell someone your plan. Follow national park rules for where you may stay at night. The stargazing trip checklist has the full list. I build Sky Map, so take the tip with that in mind: download it before you lose signal, because its core sky map works without internet, and check Tonight’s Sky Conditions (cloud cover, humidity, best time) the afternoon before. For a red screen use iPhone Color Filters (how).

North of the border: Big Bend, Death Valley.

Sources: UNAM Instituto de Astronomía visitor pages (astronomia.unam.mx/observatorio-spm/visitantes/, astrossp.unam.mx), visitor policy PDF (astrossp.unam.mx), checked 2026-10-27.