Visible Multi Object Spectrograph

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{{Short description|Wide field imager and multi-object spectrograph at the VLT in Chile}}

File:Vimos-VLT.jpg

The Visible Multi-Object Spectrograph (VIMOS) is a wide field imager and a multi-object spectrograph installed at the European Southern Observatory's Very Large Telescope (VLT), in Chile. The instrument used for deep astronomical surveys delivers visible images and spectra of up to 1,000 galaxies at a time.{{cite web |url=https://www.eso.org/sci/facilities/paranal/instruments/vimos.html |title=VIMOS – Visible Multi Object Spectrograph (Summary) |work=ESO |date=19 December 2013 |access-date=2 August 2015}}{{cite web |url=https://www.eso.org/sci/facilities/paranal/instruments/vimos/overview.html |title=VIMOS – General Description (Overview) |work=ESO |date=23 March 2013 |access-date=2 August 2015}} VIMOS images four rectangular areas of the sky, 7 by 8 arcminutes each, with gaps of 2 arcminutes between them. Its principal investigator was Olivier Le Fèvre.

The Franco-Italian instrument operates in the visible part of the spectrum from 360 to 1000 nanometers (nm). In the conceptual design phase, the multi-object spectrograph then called VIRMOS included an additional instrument, NIMOS, operating in the near-infrared spectrum of 1100–1800 nm.{{cite web |url=https://www.eso.org/sci/publications/messenger/archive/no.91-mar98/messenger-no91-16-17.pdf |title=VIMOS and NIRMOS: Status Report |work=ESO |format=PDF |date=March 1998}}

Operating in the three different observation modes, direct imaging, multi-slit spectroscopy, and integral field spectroscopy, the main objective of the instrument is to study the early universe through massive redshift surveys, such as the VIMOS-VLT Deep Survey.{{cite web |url=https://www.eso.org/public/unitedkingdom/news/eso0804/ |title=New Light on Dark Energy—Probing the cosmic Web of the Universe |work=ESO |date=30 January 2008 |type=eso0804, Science Release}}

VIMOS saw its first light on 26 February 2002, and has since been mounted on the Nasmyth B focus of VLT's Melipal unit telescope (UT3).{{cite web |url=https://www.eso.org/public/unitedkingdom/teles-instr/vlt/vlt-instr/vimos/ |title=VIMOS—Visible Multi-Object Spectrograph |work=ESO |access-date=2 August 2015}}{{cite web |url=https://www.eso.org/public/unitedkingdom/news/eso0209/ |title=VIMOS—a Cosmology Machine for the VLT. Successful Test Observations With Powerful New Instrument at Paranal |work=ESO |date=13 March 2002 |type=eso0209, Science Release}}

It was retired in 2018 to make space for the return of CRIRES+.{{cite web |title=Paranal – decommissioned instruments |url=https://www.eso.org/sci/facilities/paranal/decommissioned.html |access-date=21 July 2021}}

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