MOONS - the Multi-Object Optical and Near-infrared Spectrograph
23 Apr 2018



MOONS is a unique, visible and near-IR multi-object spectrograph that will be operated on the VLT in the early 2020s.



In labs across Europe and Chile we are currently building MOONS, the Multi-Object Optical and Near-infrared Spectrograph. In a few years time, this remarkable instrument will become the next generation spectrograph for ESO's Very Large Telescope (VLT) in Chile, giving astronomers a new way to study our Universe.

MOONS is able to simultaneously observe 1000 objects, delivering spectra from the optical to the near-infrared in a single exposure. When combined with the huge collecting area of the VLT, MOONS will provide the observational power necessary to study galaxy formation and evolution, over the entire history of the Universe. At the same time, the high spectral resolution mode will allow astronomers to study chemical abundances of stars in our Galaxy, in particular in the highly obscured regions of the Galactic centre.

The image shows what MOONS will look like when at the VLT. At the heart of instrument lie 1000 small robotic positioners that will be used to precisely align optical fibres with the object of interest on the sky. Light is then fed along these fibres into the spectrograph (the large blue box in the image), where the light is split using dichroics into three different wavelength channels, before being dispersed to simultaneously deliver spectra in each channel. A summary of the instrument's main properties is given in the table below.

MOONS is being built by 10 different institutions, spread across six different countries. The project is being managed and led by STFC at the UK Astronomy Technology Centre in Edinburgh. The consortium partners are each building different parts of the instrument all of which will be brought together and assembled in Edinburgh over the next few years. Once completed and fully tested MOONS will be shipped to the telescope to begin its scientific operations, allowing astronomers to build maps of our Galaxy and our Universe in previously unexplored ways.​​

TelescopeVery Large Telescope
Total instrument field of view500 acrmin2
On-sky diameter of each 1.2 arcsec
Close packingTwo fibres to within 10 arcsec
Observing modesMedium resolution (MR) and high resolution (HR)
Simultaneous wavelength in MR0.64μm – 1.8μm
Spectral resolution in MRR ~ 4000 - 6000
Wavelength in HR (in 3 regions){0.76 – 0.88μm} + {0.95 – 1.3μm} + {1.5 – 1.64μm}
Spectral resolution in HR{R ~ 9,000}    +     {R ~ 4,500}   +   {R ~ 18,000}

For more information about MOONS, click here.​