31 2.6 N, 115 27.8 W
(Copy and paste this location into maps.google or earth.google for images and maps of site.)
2830 meters (9285 feet)
San Pedro Martir is located in northern Baja California, Mexico, inside a national park and is the site of the Observatorio Astronomico Nacional de San Pedro Martir. It is a medium-elevation site (2830 m), 65 km from the Pacific coast in the west and 55 km from the Sea of Cortez (Gulf of California) to the east. The terrain is gently rising from the north, west and south, with a steep cliff dropping more than 2000 m to the desert in the east. The highest point of the area and, in fact, of Baja California, Picacho del Diablo (3095 m or 10,154 ft), is approximately 6 km to the south-east of the observatory. The closest town is Ensenada (300,000 inhabitants) at 4 hours driving time and 140 km line-of-sight distance. The closest commercial airports are in Tijuana (at 220 km) and San Diego (250 km). There is an existing road all the way to the observatory. It is paved to the national park entrance. The last 80 km to the site are unpaved (the road may need to be paved to support vehicles carrying heavy equipment). The site itself is in a pine forest. Roads exist between the offices and domes of the National Observatory; the existing offices and lodges are 4 kilometers from the existing telescopes. Additional lodges and roads (at least kilometer) would have to be built to accommodate a new, large telescope.
View of the dome of the building that houses the 0.84m telescope in the National Observatory located in Sierra San Pedro Martir, Baja California, Mexico. Photo credit: Jamie Sanchez Diaz.
Devil’s Peak as seen from the Mexican National Astronomical Observatory. Photo credit: Jamie Sanchez Diaz.
The steep drop-off to the east seen from 2.12-meter site at San Pedro Martir. San Felipe and the Sea of Cortez (Gulf of California)can be seen in the distance. Photo credit: Jamie Sanchez Diaz.
View of the Cerro Palado test site, located about 0.5 km from the 2.1-meter dome on San Pedro Martir. The observing tower set up by the Thirty Meter Telescope project is visible to the left of center. Photo credit: TMT project.
The site is in a pine forest and receives significant annual precipitation, but most of that comes down in a small number of strong events with mostly clear time in between.
Seeing data are not available yet online. The following data were presented in a professional paper by J. Bohigas of the Instituto de Astronomia, Universidad Nacional Autonomia de Mexico, Ensenada, B. C., Mexico.
Typical seeing data for one night during an observational run that was made during October 27 and November 19, 2006. Graph from Bohigas et al. (2008). Also shown are data from the TMT project taken at the same time.
Average seeing data for each night during the observational run October 27 and November 19, 2006. Graph from Bohigas et al. (2008). Also shown are data from the TMT project taken at the same time.
Data on the number of clear nights at San Pedro Martir are not yet available online. The following data were presented in a professional paper by Mauricio Tapia of the Instituto de Astronomia, Universidad Nacional Autonomia de Mexico, Ensenada, B. C., Mexico.
Average monthly fraction of clear nights at 2.1-meter dome at San Pedro Martir from 1984 to 2002. “Photometric” is defined as nights with the percentage of cloud cover as 15% or less. “Spectroscopic is defined as nights with the percentage of cloud cover as 65% or less.
(See humidity measurements on weather site below.)
Current and recent weather conditions (temperature, wind speed, humidity, etc.) at the National Observatory can be found at their web site.