Cerro Pachón is a mountain in central Chile, located east of the city of La Serena in the Coquimbo Region. The mountain is seismically active, with a magnitude 5.6 earthquake impacting the summit on April 30, 2012. Along with Cerro Tololo, this mountain forms part of the surrounding El Totoral Reserve that is owned by the Association of Universities for Research in Astronomy (AURA) Observatory. It is the site of the 8.1 m Gemini South Telescope of the Gemini Observatory, the 4.1 m SOAR optical imager, and the 8.4 m Vera C. Rubin Observatory.
The mountain site has arid, desert conditions with cacti, shrubs, and wildflowers dotting the landscape. It is host to fauna that include Andean condor, viscachas, and the occasional fox, as well as typical desert species such as lizards, snakes, spiders, and scorpions. There is a rock art site thought to associated with the El Molle culture, 300 BC to 800 AD.