ESO Signs Agreement to Build MOONS

ESO has signed an agreement with a consortium led by the Science and Technology Facilities Council’s UK Astronomy Technology Centre (UK ATC) to build MOONS — a unique new instrument for ESO’s Very Large Telescope (VLT). MOONS will be able to tackle some of the most compelling astronomical questions such as probing the structure of the Milky Way and tracing how stars and galaxies form and evolve. During its ten-year design lifetime, MOONS is expected to observe of order ten million objects.  

MOONS [1] stands for Multi-Object Optical and Near-infrared Spectrograph. This complex instrument will collect light from many objects at the same time, using up to 1000 fibres over a large field of view, and will work at both visible light and near-infrared wavelengths. The power of the VLT, combined with the unique capabilities of MOONS, will provide the tools necessary to study galaxy formation and evolution over most of the history of the Universe [2].

As well as studies of the distant Universe, the infrared capabilities of MOONS will allow astronomers to study the highly obscured regions of the bulge of our galaxy. In combination with the power of the VLT, it will observe stars within the Milky Way up to a distance of about 40 000 light-years, looking through the Bulge and Disc to reveal their structure to create a three-dimensional map of our galaxy [3].

In 2010, ESO asked for suggestions from its community for a wide-field spectrometer. Two concepts, MOONS (Multi-Object Optical and Near-infrared Spectrograph) and 4MOST (4-metre Multi-Object Spectroscopic Telescope) were reviewed in 2013 and selected to proceed to a design and construction phase with MOONS scheduled for first light in 2018 and 4MOST in 2019.

MOONS will also provide the crucial spectroscopic follow-up for the European Space Agency (ESA)’s Gaia mission and for other ground based optical and near-infrared imaging surveys (VISTA, UKIDSS, VST, Pan-STARRS, Dark Energy Survey, LSST), as well as facilities operating at other wavelengths (ALMA, Herschel, eRosita, LOFAR, WISE, ASKAP). As such, it will fill a critical gap in the astronomical toolkit, particularly in the near-infrared.

MOONS will also play an important role for the recently approved ESA mission Euclid, covering the same spectral range as its space observations and will support its calibration. It will perfectly complement ongoing and planned surveys including the new large Gaia–ESO public spectro­scopic survey [4], where optical spectroscopy is being performed by FLAMES and VIMOS.

Notes

[1] The MOONS project brings together scientists and engineers in a consortium led by the Science and Technology Facilities Council – UK Astronomy Technology Centre, Royal Observatory, Edinburgh, United Kingdom; and including CAAUL – Centre for Astronomy and Astrophysics of University of Lisbon, Portugal; GEPI, Observatoire de Paris, France; Italian National Institute for Astrophysics (INAF) with its centres in Florence, Bologna, Milan and Rome, Italy; AIUC, Centre for Astro-Engineering, Pontificia Universidad Católica de Chile, Santiago Chile; Cavendish Laboratory and Institute of Astronomy, University of Cambridge, United Kingdom; ETH Zürich, Institute for Astronomy, Switzerland; the University of Geneva, through its Astronomical Observatory, Sauverny, Switzerland and ESO.

[2] A very strong scientific case for the development of a wide-field, spectrometer that could observe many objects simultaneously at both visible and near-infrared wavelengths has existed for many years and was a high priority of ASTRONET —  a comprehensive long-term plan for the development of European astronomy. Such an instrument is considered much-needed to complement existing wide-field imaging surveys. 

ASTRONET was created by a group of European funding agencies in order to establish a strategic planning mechanism for all of European astronomy and it has published a comprehensive science vision and infrastructure roadmap.

[3] This is difficult because the Earth is in the middle of the disc of the Milky Way, so the process is a little like trying to map a forest from the inside.

[4] Gaia-ESO is an ESO public spectroscopic survey, targeting more than 100 000 stars with the FLAMES optical multi-fibre spectrograph, systematically covering all major components of the Milky Way, from halo to star-forming regions.