COMPLEJO ASTRONÓMICO EL LEONCITO - COMPLEXE ASTRONOMIQUE DE LEONCITO

The Leoncito Astronomical Complex (CASLEO) is located in a site called "El Leoncito" (or "Parque Nacional El Leoncito") characterized by the high quality of its night sky (low light pollution), very favourable meteorological statistics (with more than 250 clear nights per year), and a transparent and dry atmosphere favourable to high-level observations (the Chilean border is not very far away.... enough to share some of its exceptional sky). Leoncito is located more precisely in the province of San Juan, in the department of Calingasta, about 40 km southeast of the city of Barreal, in front of a geological formation called "Barreal Blanco", a former lake basin now dry, quite spectacular. The observatory itself is located on the heights, at an altitude of 2,552 m, on the western foothills of the Sierra del Tontal, which serve, in a way, as a natural barrier to the few light pollution emanating from the city of San Juan. It should be noted in passing that Argentines are obviously not banter with the preservation of the night sky, since it is by law that the quality of the sky has been preserved in this region since 1993 (France should take inspiration from such decisions to limit the proliferation of unwanted and unnecessary lighting throughout its territory). At such an altitude and in such a remote site it is essential for astronomers to have a minimum of infrastructure guaranteeing complete autonomy over several days.... Thus, in addition to the main dome, other buildings are visible below on the site, such as bedrooms, dining rooms, kitchens, meeting rooms, leisure rooms, administrative services, etc. The autonomy is so important that the place even has its own power plant! The CASLEO was officially created in May 1983 to provide Argentine astronomers with a first-rate research tool within the framework of the National Council for Scientific and Technical Research. The telescope housed under the dome has a diameter of 215 cm and a weight of 40 tons. It was built by the National University of La Plata and named the "Jorge Sahade" telescope in honour of this illustrious Argentine astrophysicist who was President of the International Astronomical Union from 1985 to 1988. It was inaugurated on 12 September 1986 by the President of the Argentine Republic Raúl Alfonsín.

This beautiful giant telescope would not be as interesting if we couldn't visit it... Fortunately, CASLEO popularizes astronomy and offers some 6,000 visitors a year to discover the facilities and understand the work done by scientists on site. Guided tours of about forty minutes are on the menu. Better still, every month on several occasions, night tours are offered.... Visitors must then arrive at the complex by their own means around 5pm. They are then received by a guide who accompanies them for a tour of the facilities, the "Jorge Sahade" telescope and other related facilities. The evening also includes dinner, followed by observations of the sky according to the cloud cover, in a 350 mm diameter telescope installed for the occasion. At such a low latitude (31° south), the objects of the southern sky appear in all their splendour.... It is also essential to come on an evening without an annoying Moon (phase between the last quarter and the new moon), so that the light from our satellite does not penalize the vision of the weakest celestial objects. The duration of the observations then depends... only on the motivation of the curious who come to observe! And once the equipment is repacked, it is possible to sleep at the observatory! The only constraint: to come warmly dressed, an imperative given the altitude of the site and its typical mountainous climate. Even if this observatory is not the most spectacular in the world, the quality of its welcome guarantees unforgettable memories for the enthusiastic astronomer.