The planned site is within the National Astronomical Observatory of Mexico (San Pedro Mártir, SPM) at coordinates 31° 02′ 41.52″ N / 115° 27′ 52.13″ W, with an altitude of approximately 2,830 meters. The site is above the atmospheric inversion layer and features a dry, stable climate with excellent observing conditions, allowing for an average of 300 observable nights per year.
- Seeing: ~0.6 arcsec
- Clear Night Rate: ~80% of nights meet spectroscopic conditions, and ~70% meet photometric conditions
- Sky Brightness: Up to 21 mag (V = 21.5 mag/sq. arcsec, R = 20.7 mag/sq. arcsec)
The Site Environmental Impact Assessment (DTU) was submitted to SEMARNAT (Secretaría de Medio Ambiente y Recursos Naturales, Mexico’s Secretariat of Environment and Natural Resources) in 2025 and is now in the final stage of compensation measure negotiations. Approval is expected by the end of the year. Following this, UNAM will apply to local authorities for all necessary development permits, allowing construction to begin.
Due to challenging winter conditions, including snow and difficult road access, construction efficiency is low. Based on UNAM’s recommendation, site construction is scheduled to start in spring 2026, with an estimated duration of approximately 10 months.
Planned Site
