On 7 March 2019, ESO officially became a shareholder of the Cherenkov Telescope Array Observatory gGmbH (CTAO). The necessary formal steps were concluded during the meeting of the CTA Council on 7–8 March at ESO’s headquarters in Garching bei München, Germany, after ESO had participated in the project for some time as an observer.

ESO already signed an agreement on 19 December 2018 to host the southern site of the CTA in the Atacama desert near the ESO Paranal Observatory in Chile. The Paranal site, home of the Very Large Telescope, offers excellent viewing conditions and well-established infrastructure, making it an attractive location for new facilities such as CTA–South. The northern site of the CTA will be based on La Palma in the Canary Islands.

As a shareholder, ESO will be represented at the CTA Council, which shall govern the observatory, joining shareholders from 11 countries and associate members from another two. The current legal entity is the CTAO gGmbH, a German non-profit limited liability company. The participating countries are currently in the process of establishing the CTAO European Research Infrastructure Consortium (CTAO ERIC) which will construct, commission and operate for an intended period of 30 years the immense observatory.