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Cerro Tololo Inter-American Observatory

CTIO is the southern-most of three major observatories in the Chilean Andes, in the area of La Serena (which are Las Campanas to the North, La Silla in the middle and CTIO itself). It is located on a mountain top near Vicuna, within sight of La Silla observatory. I visited it once - and forgot to take along my camera... This is why I can show here only one photo that I took during a fly-by on the way to La Silla (taken on another trip).

Cerro Tololo, as seen from a small airplane flying to the landing strip of La Silla observatory. What one cannot see in this photo is that the mountains normally, in sunlight, show all kinds of colours from minerals at the surface. The Andes are the most mineral-rich mountain range on Earth. Their metal content is so high that even the Earth's magnetic field and associated radiation belts are distorted in that region (the so-called "South Atlantic Anomaly").

Note that, in good conditions, one can actually see La Silla towards the North from Cerro Tololo. The largest of the domes at CTIO hosts a 4-m telescope. At closer range the observatory looks as shown below. As a nice extra one can see the Large Magellanic Cloud as a diffuse stripe on the sky.

Nighttime photo of CTIO with star tracks, including the Large Magellanic Cloud, in the background (photo courtesy Norbert Zacharias).

The site of the southern Gemini telescope, although not visible in the photo (it did not exist at the time), is close to CTIO, on a neighbouring mountain ridge.