On the mountain

The continuing adventures of the Pea hunting trip to Chile…

An hour’s flight from Santiago to La Serena, followed by a 2 hour drive, and we arrived at La Silla in time for a tasty lunch (notable lack of peas, though). We then had a meeting with our support astronomer to check our plans for the upcoming observing run and make sure we had filled in all the necessary forms. He also kindly gave us a tour of the three biggest telescopes, including the NTT which we will be using. I’ve been here a couple of times before, but always using the NTT, so it was nice to see the other main telescopes, and get some great views from their dome catwalks.

View of the La Silla landscape from my room

The landscape around La Silla is red, arid and lumpy. Dry red soil strewn with small rocks, covering many hills of different sizes which appear to be piled on top of one another to form larger peaks. Although this is the edge of a desert, the landscape is dotted by small bushes, though many look more like collections of twigs than living plants.

La Silla observatory was set up in the early Sixties. Like other sites from the same era, such as La Palma, Kitt Peak and Siding Spring, it sports a collection of telescope enclosures of various shapes and sizes. Although the traditional dome is most common, it seems the discerning enclosure has an element of squareness, the degree of which varies with construction date like a fashion.

The telescopes here have apertures varying from half a metre to 3.6 metres. Although the atmospheric conditions at La Silla are very good, they weren’t considered exceptional enough to site the latest generation of 8 metre telescopes here. Instead ESO chose to develop a new observatory at Paranal. When you’re pushing technological and scientific limits, and spending the amount of money that requires, you need to be very careful choosing your site to maximise the quantity and quality of observations that are possible. As science has advanced and typical astronomical observations have become more challenging, the numerous small telescopes around the world are being used less and less. In fact, most of the domes on La Silla are either empty or contain telescopes that are no longer in routine service.

Visiting astronomers usually arrive on the mountain at least one night before their observations begin, to prepare final details and adjust to nocturnal working. We actually have two full days and nights here before we start using the telescope. That will give us plenty of time to review and refine our initial list of targets, although we will certainly still need to adapt our plans once we start taking data. We’ve now got our list of high priority targets organised, and tomorrow we’ll decide upon other interesting objects that it would be useful to observe, if everything else is going well.