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The construction of the ESO's Extremely Large Telescope (ELT) passed it 50% completion milestone in 2023. There has been good progress on all fronts over the past two years. The construction site at Armazones (Chile) went from a flat landscape dominated by rocks and lean concrete to a mountain top housing finished structural concrete foundations and an 80m-high dome steel structure. In Europe, the manufacturing of the telescope structure is half complete; tens of M1 segments have been polished to excellent optical quality; the M2 mirror is quickly approaching its final figuring accuracy; the M4 adaptive mirror has received all its six Zerodur® thin shells and is progressing to full laboratory integration; the M5 has reached a critical step with the brazing of the six CVD-coated SiC petals; the two large Pre-focal Stations are close to start their final testing; the four instruments are all in final design phase with some having started procurement and more. This paper summarizes the current status of the ESO's ELT Construction.
Tamai et al. (Wed,) studied this question.