ESO has taken a step towards the construction of a powerful new instrument — the Enhanced Resolution Imager and Spectrograph (ERIS) — to be installed on Unit Telescope 4 of ESO’s Very Large Telescope at Cerro Paranal in northern Chile.
Following the conclusion of the call for proposals, the project will be carried out by ESO in partnership with the Max Planck Institute for Extraterrestrial Physics (Garching, Germany, with contributions from ETH Zürich, Switzerland) and the INAF Arcetri Astrophysical Observatory (Florence, Italy). ESO has given the go-ahead for the two collaborating institutes to start work and the project aims to achieve first light in late 2017.
ERIS — which will be active for at least ten years after it is installed — will benefit from the Adaptive Optics Facility that corrects for the blurring effects of the Earth’s atmosphere. It aims to take the sharpest direct images so far obtained using a single 8-metre class telescope . ERIS will take over the role of the very successful NACO instrument, which is approaching the end of its life.
Applications of ERIS cover many areas of astronomy, from studies of bodies within the Solar System and the observation of exoplanets out to the imaging of galaxies in the distant Universe.
As an example of a scientific objective of ERIS, it will be ideal to observe a star that will pass very close to the supermassive black hole in the centre of the Milky Way in May 2018. This star, known as S2, orbits the central black hole every sixteen years, and scientists already have data for a full orbit (eso0846, eso1151). By measuring the effect the supermassive black hole has on the star when closest to it, astronomers aim to test some of the gravitational effects predicted by Einstein’s theory of general relativity.
 Much higher resolution for certain classes of observations can be achieved by combining several telescopes using the VLT Interferometer. However ERIS is applicable to a much broader range of imaging applications, particularly on fainter targets.