Cerro Pachon, Chile

The Southern Gemini Telescope

Map of Cerro Pachon

Cerro Pachon is located 10 kilometers southeast of the Cerro Tololo Inter-American Observatory, at 2715m in the foothills of the Chilean Andes. The mountaintop is exceedingly dry, making it suitable for infrared observations. The air overhead is very stable, yielding excellent seeing. During the summer months, Cerro Pachon is often above the haze layer that can envelop lower altitudes.

The Site Plan on Cerro Pachon

Cerro Pachon is a mostly undeveloped site located on land owned by AURA. Cerro Tololo Inter-American Observatory (CTIO) is located on a nearby mountain top, within the same AURA land-holding. There are no other telescopes currently located on Cerro Pachon, but site survey work has been ongoing for several years.

The Gemini structure is located at the high point of the Pachon ridgeline. The north face is very steep, with cliffs along most of the length of the ridge. The enclosure is located on the cliff side, with the support facility directly to the south. There is now a well-developed graded earth road from Cerro Tololo to the Gemini site on Cerro Pachon, and other developments are currently underway.

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Peter Michaud / pmichaud@gemini.edu / October 29, 1998