Press Releases

27 June 2024: The European Southern Observatory’s Extremely Large Telescope (ESO’s ELT), under construction in the Chilean Atacama Desert, is one step closer to completion. German company SCHOTT has successfully delivered the blank for the last of the 949 segments commissioned for the telescope’s primary mirror (M1). With a diameter of more than 39 metres, M1 will be by far the largest mirror ever made for a telescope.

18 December 2023: The construction of the European Southern Observatory’s Extremely Large Telescope (ESO's ELT) has reached an important milestone with the delivery to ESO and shipment to Chile of the first 18 segments of the telescope’s main mirror (M1). Once they arrive in Chile, the segments will be transported to the ELT Technical Facility, at ESO’s Paranal Observatory in the country’s Atacama Desert, where they will be coated in preparation for their future installation on the telescope main structure. Unable to be physically made in one piece, M1 will consist of 798 individual segments arranged in a large hexagonal pattern, with an additional 133 being produced to facilitate the recoating of segments. With a diameter of more than 39 metres, it will be the largest telescope mirror in the world.

9 January 2018: The first six hexagonal segments for the main mirror of ESO’s Extremely Large Telescope (ELT) have been successfully cast by the German company SCHOTT at their facility in Mainz. These segments will form parts of the ELT’s 39-metre main mirror, which will have 798 segments in total when completed. The ELT will be the largest optical telescope in the world when it sees first light in 2024.

30 May 2017: Contracts for the manufacture of the 39-metre primary mirror of ESO’s Extremely Large Telescope (ELT) were signed today at a ceremony at ESO’s Headquarters near Munich. The German company SCHOTT will produce the blanks of the mirror segments, and the French company Safran Reosc will polish, mount and test the segments. The contract to polish the mirror blanks is the second-largest contract for the ELT construction and the third-largest contract ESO has ever awarded.

22 May 2017: The casting of the secondary mirror blank for ESO’s Extremely Large Telescope (ELT) has been completed by SCHOTT at Mainz, Germany. The completed mirror will be 4.2 metres in diameter and weigh 3.5 tonnes. It will be the largest secondary mirror ever employed on an optical telescope and also the largest convex mirror ever produced.

11 October 2000: Less than one month after "First Light" for the fourth 8.2-m YEPUN telescope (ESO PR 18/00), another special moment occurred at ESO's Paranal Observatory. This time, it was the first truly "underground" event, in the 168-metre long Interferometric Tunnel that has been dug beneath the platform at the top of the mountain. As one staff member remarked on this occasion, it was something like "the first scheduled trip of the Paranal metro"!

14 December 1999: On December 14, 1999, REOSC , the Optical Department of the SAGEM Group , finished the polishing of the fourth 8.2-m main mirror for the Very Large Telescope (VLT) of the European Southern Observatory. The mirror was today delivered to ESO at a ceremony at the REOSC factory in Saint Pierre du Perray, just south of Paris.

17 September 1999: Work is progressing well at ESO's Very Large Telescope (VLT) project, both at the Paranal Observatory and in Europe. Here is a brief summary with recent news from this major project, illustrated with photos from the construction.

25 February 1999: While much attention is now directed towards the VLT Opening Symposium that will take place in Antofagasta on 1-4 March 1999, assembly work on the VLT Unit Telescopes proceeds at Paranal.

17 April 1998: The world's largest optical mirror - with 8.2-m diameter and a surface of more than 50 m 2 , polished to the highest perfection - was today put in place at the First VLT Unit Telescope (UT1) at the Paranal Observatory.

12 December 1997: Just as the first 8.2-metre Zerodur VLT primary mirror (M1) is arriving at the Paranal Observatory, there are also good news about the first of the 1.2-m Beryllium VLT secondary mirrors (M2) and its Supporting Unit . This assembly is placed at the top of the VLT 'telescope tube'.

12 December 1997: Another historic event in ESO's Very Large Telescope Project has just occurred. The first giant mirror is on the mountain! The blanks for the four 8.2-metre VLT mirrors of Zerodur were produced by the Schott Glaswerke (Mainz, Germany) and have been polished at the REOSC factory (St. Pierre du Perray, France). For more information, see ESO Press Release 15/95. The first of the four mirrors left France in early November 1997 en route to Paranal. The transport was organized by the Gondrand company.

17 November 1997: After a long journey from Europe, the first Very Large Telescope mirror cell (VLT M1 cell) and a concrete 8.2-m dummy mirror were unloaded in the Port of Antofagasta on October 31, 1997. From here, they were transported by special trucks to the Paranal Observatory.

22 October 1997: During the past month, there has been much action in many different areas at the ESO Paranal Observatory. Work has continued on the assembly of various components of the telescope structures and on the surface of the summit platform, as well as in connection with the maintenance and storage facilities near the base camp at the foot of the mountain.

5 December 1995: As the ESO Very Large Telescope (VLT) rapidly takes on shape, Europe has just come one step closer to the realisation of its 556 million DEM astronomical showcase project.

13 November 1995: In 1989, the European Southern Observatory (ESO), the European Organisation for Astronomy, awarded to REOSC, a subsidiary of the SFIM Group and located in Saint Pierre du Perray (France), a comprehensive contract for the polishing of four 8.2-metre diameter mirrors for the unit telescopes of the ESO Very Large Telescope (VLT) project. These mirrors are the largest ever manufactured and polished. This contract comprises not only the polishing and high-precision optical testing of each giant mirror, but also the safe condition of transportation of the blanks which were manufactured by Schott Glaswerke in Mainz (Germany). In order to fulfill the contract, REOSC conceived, built and equipped a novel, high-tech workshop which would allow to polish and test the mirrors, each of which has a surface area of more than 50 square metres.

29 September 1994: During the past months, vast progress has been made in the construction of ESO's 16-metre equivalent Very Large Telescope (VLT). This major scientific and technological project aims at installing the world's largest optical telescope in the form of four interconnected telescopes with 8.2-metre mirrors on the Paranal mountain in the Chilean Atacama desert. It continues to be on schedule as it heads towards its completion, just after the year 2000.

29 June 1993: On June 25, 1993, Schott Glaswerke (Mainz, Germany) officially handed over to ESO the largest mirror blank ever made. Weighing 22,000 kilograms and with a diameter of 8.2 metres, the blank has a thickness of only 177 millimetres.

21 April 1992: On April 24, 1992, the French Minister for Research and Space, Professor Hubert Curien, will inaugurate a unique, new optical facility of R.E.O.S.C [2] , at Saint Pierre du Perray, near Paris. The delicate polishing of the giant mirrors for ESO's 16-metre equivalent Very Large Telescope (VLT) will take place here.