VLT

Four 8.2 m Unit Telescopes and four movable 1.8 m Auxiliary Telescopes on Cerro Paranal, with instruments from the near-ultraviolet to the mid-infrared, many with adaptive opticsadaptive opticsCorrecting atmospheric distortion in real time with a deformable mirror driven by a wavefront sensor, at kilohertz rates, using a bright natural star or a laser guide star. Brings large ground telescopes close to their diffraction limit in the infrared.: MUSE (integral-field spectroscopyintegral field unitA spectrograph front end that slices a small field into many elements and takes a spectrum of each, giving a data cube with two spatial axes and one wavelength axis.), ESPRESSO (precision radial velocitiesradial velocityVelocity along the line of sight, from the Doppler shift of spectral lines. Planet searches measure the star's reflex motion to below 1 m s⁻¹.), SPHERE (high-contrast imaging), X-shooter, KMOS and CRIRES+. The VLT InterferometerinterferometryCombining waves from separate receivers coherently. In radio and optical astronomy, correlating signals from separated telescopes gives the resolution of one as large as their separation. In gravitational-wave detection, a laser Michelson interferometer measures tiny differential changes in its arm lengths. combines telescopes on baselinesbaselineThe separation between two antennas of an interferometer, projected onto the plane perpendicular to the source. Long baselines give fine resolution; short ones recover extended emission. up to 130 m with the Unit Telescopes and 200 m with the Auxiliary Telescopes; its GRAVITY instrument tracks stars orbiting Sgr A* at tens of µasarcsecond1/3600 of a degree (″). A milliarcsecond (mas) is 10⁻³″ and a microarcsecond (µas) 10⁻⁶″. Atmospheric seeing limits ground telescopes to about 0.5–1″ without adaptive optics..

Operator

ESO

Site

Cerro Paranal, Chile

Aperture

4 × 8.2 m

Passband

0.3 µm – 20 µm

First light

25 May 1998