If it is your first time observing, you arrive one or two nights in advance to learn how to use the instrument, familiarize with the telescope/instrument control software and to prepare the observations (list of targets, strategy, etc). During my nights off, if it’s clear, I take my camera to shoot pictures of the starry southern sky!

Each observatory is different, but they all have common things such as a hotel to accommodate the staff and visiting astronomers and a big dining room/kitchen. If you like watching movies or reading a book there is a good catalog you might want to check (especially if it snows!).

One of the best things about observing is the food. It includes all sorts of meals and desserts (a lot of chilean “manjar“!). Usually, before sunset we all get together in the dining room to have dinner. This is a good opportunity to meet and talk with other astronomers from around the world. Depending on the observatory, on Sundays they will serve special meals like “empanadas” or chilean barbecue.

Normally, my ‘day’ starts at 4 p.m. when I have to initialize the calibrations. The night officially starts after sunset and ends when the Sun is up again, so I go to bed around 8 a.m. La Silla, for example, has a big control room with workstations dedicated to the different telescopes. In fact, the ESO-3.6m telescope, in which HARPS is installed, is about 3 km away from the control room. The high-resolution spectrograph HARPS is located in a separate room where the temperature and pressure are stabilized. These conditions allow the instrument to achieve precision below 1 m/s. But, what this number means? This precision is the key to detect Earth-mass exoplanets. A planet orbiting a star causes the star’s spectral lines (i.e. the specific pattern of lines that each star produces in a spectrograph) to move in time. The shift of the star’s spectral lines is proportional to the mass of the planet and 1 m/s precision ensures we can detect small exoplanets with masses similar to that of the Earth.

As I was saying, I operate the instrument from the control room. The Telescope Operator controls the telescope while I set up the target list and all the exposure parameters of the instrument. For HARPS, there is a great reduction system that allows you to visualize how your data is processed as soon as the exposure finishes. The number of stars I observe in a typical night varies depending on factors such as weather conditions and brightness of the stars. Typically I am able to observe between 30 and 40 stars in one night.