Extremely Large Telescope
03 Nov 2023



The UK ATC is working on multiple instruments for the ELT: HARMONI, METIS, ANDES and MOSAIC

The construction of the Extremely Large Telescope seen in silhouette with the sun burning bright behind.



​The Extremely Large Telescope (ELT) is one of the European Southern Observatory's (ESO) biggest and most ambitious projects. Currently being built in Chile the ELT is a groundbreaking ground-based telescope boasting a massive 39-metre main mirror, making it the largest visible and infrared light telescope on Earth. Beyond its unparalleled size, the ELT will sport a suite of cutting-edge instruments. ​​​

The UK ATC is playing key roles in four of the six instruments currently being designed for the ELT.

​​​The ELT's​ first light is expected in 2028.​The construction of the Extremely Large Telescope in the desert in Chile.

HARMONI (High Angular Resolution Monolithic Optical and Near-infrared Integral field Spectrograph)

HARMONI is an Adaptive Optics assisted Integral Field Spectrograph. It separates an astronomical image into multiple spatial elements, with unprecedented resolution, to then disperse each one of them into individual wavelengths using a powerful spectrograph. Providing this unique spatial resolution means HARMONI will revolutionize our understanding of the physical properties, chemical composition, and dynamics of many astrophysical sources, from the near Solar system objects to the far early Universe.

UK ATC leads the management of the HARMONI project to then lead the assembly and testing of the integral field spectrograph in the labs in Edinburgh.​

Find out more about HARMONI.

METIS (Mid-infrared ELT Imager and Spectrograph)

Named after the Greek god of wisdom METIS is an imager and spectrograph that operates in the mid-infrared wavelength range. One of the areas METIS will specialise in is investigating the physical and chemical properties of exoplanets alongside the study of Solar System objects, circumstellar discs and star forming regions, properties of brown dwarfs, the centre of the Milky Way, the environment of evolved stars, and active galactic nuclei. 

UK ATC​ is carrying out the design and construction of the LM-band spectrometer for METIS.

Find out more about METIS.

ANDES (ArmazoNes high Dispersion Echelle Spectrograph)

Formerly known as HIRES, ANDES is a powerful high-resolution spectrograph, dispersing the light of astronomical objects in impressive detail, allowing scientists to not only cover the wide domain of astrophysics but to also address some of the fundamental questions of physics. ANDES science goals include the detection of life signatures from Earth-like exoplanets, the search for the oldest stars in the Universe, testing​ for possible variations of the fundamental constants of physics, and the direct detection of the acceleration of the expansion of the Universe.

At UK ATC we are leading the design and construction of the near-infrared spectrograph.

Find out more about ANDES.


MOSAIC is the planned multi-object spectrograph for ELT. Conceived as a workhorse instrument, it will be the only instrument making use of the full adaptive optics-corrected field of view of the telescope. With a planned first light in the 2030s, MOSAIC will measure light from 100s of objects simultaneously. It will enable unique spectroscopic surveys of the faintest sources, from the oldest stars in the Galaxy and beyond, to the first populations of galaxies that completed the reionisation of the Universe; while simultaneously opening up a wide discovery space and providing enormous synergies with upcoming multi-wavelength facilities (including Euclid, Rubin, Roman, SKAO​).

The UK ATC provides scientific leadership for MOSAIC and is in charge of developing the laser guide star system that improves the image quality across the ELT's field of view.

Find out more about MOSAIC.