Guardian of stars

“El Leoncito” National Park is located at 40 km from Barreal in the Argentine province of San Juan, in the municipality of Calingasta. Inside the park and taking advantage of the characteristics of the sky in the place – more than 250 cloudless nights, without wind and pollution – “El Leoncito” Astronomical Complex (CASLEO, CONICET-UNLP-UNC-UNSJ) was built. From its inauguration in 1986, the complex is every year visited by astronomers from all parts of the world who attend the place to observe the sky in those powerful telescopes.

In this interview, Gil-Hutton, CONICET independent researcher at the CASLEO, describes the characteristics of the Institute and the work carried out by technicians and astronomers.

Which are the functions of the Complex?

The main objective of the CASLEO is to serve the astronomical community by providing people with the equipment to work. The second aim is to facilitate the studies conducted by the researchers who belong to the institution; and the third activity is the dissemination and promotion of astronomy.

Why was that place chosen to build the CASLEO?

Because for astronomic observation it is necessary to have certain height on the sea level to reduce partly water vapor, to ensure the clarity of the atmosphere and have an acceptable number of cloudless nights. The problem is that this type of conditions are cyclical and do not tend to be maintained throughout time. Technically, nowadays, in order to have an observatory in which those characteristics could be guaranteed for a long time, the place will have to be an island in the middle of the ocean because, among other reasons, the atmospheric flow above to the ocean runs without turbulences as it does not have any type of obstacle. In Argentina, the main disruption is the Andes Mountain Range because the atmospheric flow that comes above the Pacific Ocean, passing above Chile hits the mountain range and causes turbulences in our side. As a result, the conditions in Argentina are not ideal but San Juan is well qualified. The CASLEO receives the Argentine astronomical community as well as people from Europe, Latin America and North America.

What is the equipment at the CASLEO?

The Complex in high mountain area – there is another one in the city of San Juan – has large and visible and small equipment all distributed over an area of 405 hectares. We have astronomical equipment such as telescopes, and other that belong to the Earth science that are used by geophysics o geologists that study the earth’s magnetic and electric fields or the movement of the earth’s crust by studying the position of the artificial satellites of the Earth. There is a white building that holds the largest optical telescope in Argentina “Jorge Sahade” with a 2.15m diameter and 40 tons. It is the biggest telescope we have but there is smaller equipment at the Burek Cerro, 5km away.

How can an astronomer gain access to the telescopes at the CASLEO?

They have to submit a scientific project in advance so as to allow the appointment committee to study it and decide whether the time will be given or not. It is necessary to check if what the astronomer wants is reasonable and doable with the current equipment. The astronomer needs to have decided what he or she is going to do six months in advance, and the committee decides if the observation turn will be assigned or not. Generally, the turns take at least one week and if something unforeseen happens and he cannot attend, the task can be done with an specialized technician.

Can the telescopes be operated remotely?

Yes, they can. The observation is a technical and unpleasant task which implies gathering information that will used to conduct research but not all astronomers enjoy doing that job because it is necessary to spend the night awake, sometimes in winter and at 2.500 high. In the mountain, people have to loose contact with their homes and daily activities. Remote observation allows people to continue with their ordinary activities. As astronomers observe the screen between 8 and 10 hours, there is not a great difference between being there or doing it remotely in your house or workplace. It is more comfortable and technically the same because in high mountain one is not with the telescope, it is a control room with computers.

How do you perform dissemination tasks?

Every year, 5 and 6 thousand people visit the CASLEO. There are two types of visits, the daytime one, which is carried out during the day and the nocturnal one, which can be done in different ways, even staying overnight in the facilities of the observatory. This type of visit is more directed to people who are more interested or like astronomy, or want to see how an astronomer lives. Furthermore, public institutions such as schools, retired people associations, and tourist group from abroad, and astronomy students of Argentine universities with astronomy course of study and come to have some experience in observational astronomy.

What is the importance of doing this type of activities?

It is sometimes difficult to explain what astronomy is for and invest money in it. It is good to explain to visitors what one is doing, the objective and the cost. It is vital to explain people why one is spending public money in a certain study.

What are the lines of research of the CASLEO astronomers?

They are all inside the planetary sciences group that was created at the Institute and study how the planetary systems are formed and evolve. We have two different lines of research, a theoretical one in which scientists study how a planetary system is formed and evolves through numerical simulations in one computer. The second line of research is an observational one and involves the study of objects in our Solar System to understand how crashes in the system affect the evolution of planets. Researchers are still studying how planets are formed but they know that their evolution is the result of a crashes process that leave different kind of traces on their surfaces and can modify their orbits, that is to say, how they move around the central star. This collision is never ending, there is a huge number of small objects that crash with the planets, and among themselves, and in the case of our Solar System, they are a threat for the Earth. 60 millions of years ago, one asteroid collided with the Earth and the dinosaurs extinguished. When can something like that happen again? We do not know it because the population of small objects that surround the Earth are not completely known.