New Technology Telescope
Encyclopedia
The New Technology Telescope or NTT is an Alt-Az, 3.58-metre Richey-Chretien telescope part of the European Southern Observatory
and began operations in 1989. It is located in Chile
at the La Silla Observatory
and was an early pioneer on the use of active optics. The telescope and its enclosure developed a revolutionary design for optimal image quality.
Although other pre-existing telescopes such as the Nordic Optical Telescope
had lightweight mirrors supported by actuators, the NTT is claimed to be the first telescope using full active optics. Its design as well as the design of its enclosure (the building protecting it) included many revolutionary features, from whence it was named. In particular, great care was taken to ensure a good ventilation of the telescope, and to avoid heat sources in around the telescope. Since its construction, the NTT has undergone several upgrades which continued to improve its quality. It was used as a real-life test bench for the engineering concepts and software used for the Very Large Telescope
.
The New Technology Telescope initially had the same problem as the Hubble Space Telescope
- the mirror was ground to the wrong shape due to a mis-calibrated null corrector
. However, the active optics system of the NTT was able to correct that error without refiguring the mirror.
Perhaps most significantly, NTT observations of stars orbiting the centre of our Milky Way helped determine the mass and the radius of its supermassive black hole, effectively helping confirming the existence of such a massive and compact object.
European Southern Observatory
The European Southern Observatory is an intergovernmental research organisation for astronomy, supported by fifteen countries...
and began operations in 1989. It is located in Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
at the La Silla Observatory
La Silla Observatory
La Silla Observatory is an astronomical observatory in Chile with three telescopes built and operated by the European Southern Observatory organisation, and several others are partly maintained by ESO...
and was an early pioneer on the use of active optics. The telescope and its enclosure developed a revolutionary design for optimal image quality.
Characteristics
The main mirror of NTT is flexible and its shape is actively adjusted during observations by actuators to preserve the optimal image quality. The secondary mirror position is also actively controlled in three directions. This technology, developed by ESO, known as active optics, is now applied to all major modern telescopes, such as the Very Large Telescope at Cerro Paranal and the future European Extremely Large Telescope. The design of the octagonal enclosure housing the NTT is another technological breakthrough. The telescope dome is relatively small, and is ventilated by a system of flaps that makes air flow smoothly across the mirror, reducing turbulence and leading to sharper images.Although other pre-existing telescopes such as the Nordic Optical Telescope
Nordic Optical Telescope
The Nordic Optical Telescope is an astronomical telescope located at Roque de los Muchachos Observatory, La Palma in the Canary Islands. First light came in 1988, with regular observing beginning in 1989. It is funded by Denmark, Sweden, Iceland, Norway and Finland...
had lightweight mirrors supported by actuators, the NTT is claimed to be the first telescope using full active optics. Its design as well as the design of its enclosure (the building protecting it) included many revolutionary features, from whence it was named. In particular, great care was taken to ensure a good ventilation of the telescope, and to avoid heat sources in around the telescope. Since its construction, the NTT has undergone several upgrades which continued to improve its quality. It was used as a real-life test bench for the engineering concepts and software used for the Very Large Telescope
Very Large Telescope
The Very Large Telescope is a telescope operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. The VLT consists of four individual telescopes, each with a primary mirror 8.2m across, which are generally used separately but can be used together to...
.
Hubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...
- the mirror was ground to the wrong shape due to a mis-calibrated null corrector
Null corrector
A null corrector is an optical device used in the testing of large aspheric mirrors. A spherical mirror of any size can be tested relatively easily using standard optical components such as laser, mirrors, beamsplitters, and converging lenses. One method of doing this using a Shack cube is shown...
. However, the active optics system of the NTT was able to correct that error without refiguring the mirror.
Instruments
Currently, the NTT is equipped with 2 instruments:- SofI ("Son of ISAAC", a VLT instrument), a near infraredInfraredInfrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
camera and low-resolutionSpectral resolutionThe spectral resolution of a spectrograph, or, more generally, of a frequency spectrum, is a measure of its ability to resolve features in the electromagnetic spectrum...
spectrographSpectrographA spectrograph is an instrument that separates an incoming wave into a frequency spectrum. There are several kinds of machines referred to as spectrographs, depending on the precise nature of the waves...
, with polarimetric and high-time resolution modes - EFOSC2 (ESO Faint Object Spectrograph and Camera, v.2), a visible light camera and low-resolution spectrograph, with multi-object spectroscopy, polarimetry and coronography modes
Science with the NTT
The NTT and its instrument have contributed for important discoveries since the telescope started working at La Silla. These include unravelling the mysterious Galactic centre, contributing to the observations of the first solar-like oscillations in another star, and breaking many distance records by finding new galaxies in the far-away Universe. Most recently, the NTT helped detect a disc around a massive young star, solving the mystery of star formation in massive stars, and its observations were crucial to determine how asteroids are modified by solar wind.Perhaps most significantly, NTT observations of stars orbiting the centre of our Milky Way helped determine the mass and the radius of its supermassive black hole, effectively helping confirming the existence of such a massive and compact object.