[1] Its primary observing facility is located in El Leoncito National Park in the west of San Juan Province.

EACUC was renamed after Carlos Ulrrico Cesco on the 25th anniversary of the beginning of observations in honour of his contributions to the founding and operation of the observatory.

[2] In 1947, research started at the Lick Observatory in California to study the Northern Milky Way's structure by determining the accurate positions and apparent motions of stars.

Following a survey of potential sites, the observatory was built at El Leoncito, Argentina, near Barreal in the province of San Juan, in the eastern foothills of the Andes mountains at an elevation of approximately 2400 m (8000 ft).

The first survey of the Southern sky was made between the years 1965 and 1974, with the financial support of the National Science Foundation (NSF).

During that period, the US Naval Observatory (USNO) relocated a meridian circle telescope to El Leoncito to extend their catalogue of stellar positions to the Southern Hemisphere.