European
Southern
Observatory
About | Timeline
European
Southern
Observatory
The first observations with scientific instruments are expected to be delivered in December 2030
The ELT is set to make its first test observations in early 2029
The installation of the 798 segments that make up M1, the ELT's main mirror segments is planned to be completed in 2027.
M5 is the fifth mirror in the ELT light path. With a size of 2.7 x 2.1 metres, it is the biggest tip-tilt mirror ever employed in a telescope.
M4 is the fourth mirror in the ELT light path, and the largest adaptive mirror ever built, with a diameter of 2.4 metres.
M3, the third mirror in the ELT’s light path has a diameter of 3.75 metres.
The ELT dome is the largest telescope dome in the world. It is expected to be fully completed in early 2027.
The main structure of the ELT telescope will hold its five mirrors and instruments and is anticipated to be completed in late 2026.
The ELT's secondary mirror is expected to be completed in early-mid 2025. With a diameter of 4.25 metres, M2 will be the largest of its kind in the world.
The first 18 of the 798 segments for the ELT primary mirror arrived at the ELT Technical Facility in Chile.
In 2023, the ELT surpassed an important milestone, with more than 50% of the project completed.
Manufactured by SCHOTT, the first M1 segment blank was completed at the end of August 2018. M1 is the primary mirror of the ELT and, when completed, will be 39 metres in diameter and consist of 798 segments.
The first hexagonal segments for the main mirror of ELT were successfully cast by the German company SCHOTT.
At a ceremony in Garching bei München, Germany, ESO signed the contract with the ACe Consortium for the dome and telescope structure.
Agreement signed for the ELT's MAORY instrument, since renamed to MORFEO
ESO has signed an agreement for the design and construction of METIS
ESO’s main governing body, the Council, gave the green light for the construction of the ELT in two phases.
Part of the 3000-metre peak of Cerro Armazones was blasted away as a step towards levelling the summit in preparation for the construction of the ELT.
The civil works for the ELT began. The Chilean company, ICAFAL Ingeniería y Construcción S.A. (ICAFAL), started the construction of a road to the summit of Cerro Armazones.
The President of Chile Sebastián Piñera handed over the legal documents by which the Chilean government transferred the land around Cerro Armazones to ESO.
ESO’s governing body, the Council, met at the ESO Headquarters in Garching, Germany, and voted to start the ELT Programme.
The Republic of Chile and ESO signed an agreement regarding land for the ELT, including the donation of an area of 189 km2 around Cerro Armazones for the installation of the telescope.
Cerro Armazones was chosen as the site for the ELT by ESO's Council. Cerro Armazones is a mountain at an altitude of 3060 metres in the central part of Chile’s Atacama Desert, some 130 kilometres south of the town of Antofagasta and about 23 kilometres from Cerro Paranal, home of ESO’s Very Large Telescope.
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The European Organisation for Astronomical Research in the Southern Hemisphere (ESO) is the pre-eminent intergovernmental science and technology organisation in astronomy. It carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities for astronomy.
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