The Next-Generation Transit Survey (NGTS) is a ground-based robotic search for

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first det ...

s. The facility is located at

Paranal Observatory Paranal Observatory is an astronomical observatory operated by the European Southern Observatory (ESO). It is located in the Atacama Desert of Northern Chile on Cerro Paranal at altitude, south of Antofagasta. By total light-collecting area, ...

in the

Atacama Desert The Atacama Desert () is a desert plateau located on the Pacific Ocean, Pacific coast of South America, in the north of Chile. Stretching over a strip of land west of the Andes Mountains, it covers an area of , which increases to if the barre ...

in northern Chile, about 2 km from

ESO The European Southern Observatory is an astronomical research organisation. ESO may also refer to: *Employee stock option (also: executive stock option) *'' Ether Saga Odyssey'', a fantasy massively multiplayer online role-playing game *''The Elde ...

Very Large Telescope The Very Large Telescope (VLT) is an astronomical facility operated since 1998 by the European Southern Observatory, located on Cerro Paranal in the Atacama Desert of northern Chile. It consists of four individual telescopes, each equipped with ...

and 0.5 km from the VISTA Survey Telescope. Science operations began in early 2015. The

astronomical survey An astronomical survey is a general celestial cartography, map or astrophotography, image of a region of the sky (or of the whole sky) that lacks a specific observational target. Alternatively, an astronomical survey may comprise a set of image ...

is managed by a consortium of seven European universities and other academic institutions from Chile, Germany, Switzerland, and the United Kingdom. Prototypes of the array were tested in 2009 and 2010 on

La Palma La Palma (, ), also known as ''La isla bonita'' () and historically San Miguel de La Palma, is the most northwesterly island of the Canary Islands, a Spanish autonomous community and archipelago in Macaronesia in the North Atlantic Ocean. La Pa ...

, and from 2012 to 2014 at

Geneva Observatory The Geneva Observatory (, ) is an astronomical observatory at Sauverny (CH) in the municipality of Versoix, Canton of Geneva, in Switzerland. It shares its buildings with the astronomy department of the École Polytechnique Fédérale de Lausann ...

. The aim of NGTS is to discover

super-Earth A super-Earth is a type of exoplanet with a mass higher than Earth, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17.1 times Earth's, respectively. The term "super-Earth" refers only to t ...

s and exo-

Neptune Neptune is the eighth and farthest known planet from the Sun. It is the List of Solar System objects by size, fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 t ...

s transiting relatively bright and nearby stars with an apparent

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

of up to 13. The survey uses

transit photometry Methods of detecting exoplanets usually rely on indirect strategies – that is, they do not directly image the planet but deduce its existence from another signal. Any planet is an extremely faint light source compared to its parent star. For e ...

, which precisely measures the dimming of a star to detect the presence of a planet when it crosses in front of it. NGTS consists of an array of twelve commercial 0.2-metre telescopes ( f/2.8), each equipped with a red-sensitive

CCD CCD may refer to: Science and technology * Charge-coupled device, an electronic light sensor used in various devices including digital cameras * .ccd, the filename extension for CloneCD's CD image file * Carbonate compensation depth, a property ...

camera operating in the visible and

near-infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those of ...

at 600–900 nm. The array covers an instantaneous field of view of 96

square degree __NOTOC__ A square degree (deg2) is a non- SI unit measure of solid angle. Other denotations include ''sq. deg.'' and (°)2. Just as degrees are used to measure parts of a circle, square degrees are used to measure parts of a sphere. Analogous ...

s (8 deg² per telescope) or around 0.23% of the entire sky. NGTS builds heavily on experience with

SuperWASP WASP or Wide Angle Search for Planets is an international consortium of several academic organisations performing an ultra-wide angle search for exoplanets using transit photometry. The array of robotic telescopes aims to survey the entire sky ...

, using more sensitive detectors, refined software, and larger optics, though having a much smaller field of view. Compared to the

Kepler space telescope The Kepler space telescope is a defunct space telescope launched by NASA in 2009 to discover Earth-sized planets orbiting other stars. Named after astronomer Johannes Kepler, the spacecraft was launched into an Earth-trailing heliocentric orb ...

with its original Kepler field of 115 square degrees, the sky area covered by NGTS will be sixteen times larger, because the survey intends to scan four different fields every year over a period of four years. As a result, the sky coverage will be comparable to that of Kepler's K2 phase. NGTS is suited to ground-based photometric follow-up of exoplanet candidates from space-based telescopes such as

TESS Tess or TESS may refer to: Film and theatre * Tess (1979 film), ''Tess'' (1979 film), a 1979 film adaptation of ''Tess of the d'Urbervilles'' * Tess (2016 film), ''Tess'' (2016 film), a South African production Music * Tess (band), a Spanish pop ...

, ''Gaia'' and

PLATO Plato ( ; Greek language, Greek: , ; born BC, died 348/347 BC) was an ancient Greek philosopher of the Classical Greece, Classical period who is considered a foundational thinker in Western philosophy and an innovator of the writte ...

. In turn, larger instruments such as

HARPS The High Accuracy Radial Velocity Planet Searcher (HARPS) is a high-precision Echelle grating, echelle planet-finding spectrograph installed in 2002 on the ESO 3.6 m Telescope, ESO's 3.6m telescope at La Silla Observatory in Chile. The First l ...

ESPRESSO Espresso (, ) is a concentrated form of coffee produced by forcing hot water under high pressure through finely ground coffee beans. Originating in Italy, espresso has become one of the most popular coffee-brewing methods worldwide. It is cha ...

and

VLT-SPHERE Spectro-Polarimetric High-contrast Exoplanet REsearch (VLT-SPHERE) is an adaptive optics system and coronagraphic facility at the Very Large Telescope (VLT). It provides direct imaging as well as spectroscopic and polarimetric characterization ...

may follow-up on NGTS discoveries with a detailed characterization to measure the mass of a large number of targets using

Doppler spectroscopy Doppler spectroscopy (also known as the radial-velocity method, or colloquially, the wobble method) is an indirect method for finding extrasolar planets and brown dwarfs from radial-velocity measurements via observation of Doppler shifts in ...

(wobble method) and make it possible to determine the exoplanet's density, and hence whether it is gaseous or rocky. This detailed characterization allows to fill the gap between Earth-sized planets and

gas giant A gas giant is a giant planet composed mainly of hydrogen and helium. Jupiter and Saturn are the gas giants of the Solar System. The term "gas giant" was originally synonymous with "giant planet". However, in the 1990s, it became known that Uranu ...

s as other ground-based surveys can only detect Jupiter-sized exoplanets, and Keplers Earth-sized planets are often too far away or orbit stars too dim to allow for the planet's mass determination. NGTS's wider field of view also enables it to detect a larger number of more-massive planets around brighter stars.

Science mission

Ground-based surveys for extrasolar planets such as

WASP A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder ...

and the

HATNet Project The Hungarian Automated Telescope Network (HATNet) project is a network of six small fully automated "HAT" telescopes. The scientific goal of the project is to detect and characterize extrasolar planets using the transit method. This network is us ...

have discovered many large exoplanets, mainly Saturn- and Jupiter-sized gas giants. Space-based missions such as

CoRoT CoRoT (French: ; English: Convection, Rotation and planetary Transits) was a space telescope mission which operated from 2006 to 2013. The mission's two objectives were to search for extrasolar planets with short orbital periods, particularly t ...

and the Kepler survey have extended the results to smaller objects, including rocky super-Earth- and Neptune-sized exoplanets. Orbiting space missions have a higher accuracy of stellar brightness measurement than is possible via ground-based measurements, but they have probed a relatively small region of sky. Unfortunately, most of the smaller candidates orbit stars that are too faint for confirmation by radial-velocity measurements. The masses of these smaller candidate planets are hence either unknown or poorly constrained, such that their bulk composition cannot be estimated. By focusing on super-Earth- to Neptune-sized targets orbiting cool, small, but bright stars of K and early-M spectral type, over an area considerably larger than that covered by space missions, NGTS is intended to provide prime targets for further scrutiny by telescopes such as the

(VLT),

Extremely Large Telescope The Extremely Large Telescope (ELT) is an astronomical observatory under construction. When completed, it will be the world's largest optical and near-infrared extremely large telescope. Part of the European Southern Observatory (ESO) agency, ...

(ELT), and the

James Webb Space Telescope The James Webb Space Telescope (JWST) is a space telescope designed to conduct infrared astronomy. As the largest telescope in space, it is equipped with high-resolution and high-sensitivity instruments, allowing it to view objects too old, Lis ...

(JWST). Such targets are more readily characterized in terms of their atmospheric composition, planetary structure, and evolution than smaller targets orbiting larger stars. In follow-up observations by larger telescopes, powerful means will be available to probe the atmospheric composition of exoplanets discovered by NGTS. For example, during secondary eclipse, when the star occults the planet, a comparison between the in-transit and out-of-transit flux allows computation of a difference spectrum representing the thermal emission of the planet. Calculation of the transmission spectrum of the planet's atmosphere can be obtained by measuring the small spectral changes in the spectrum of the star that arise during the planet's transit. This technique requires an extremely high signal-to-noise ratio, and has thus far been successfully applied to only a few planets orbiting small, nearby, relatively bright stars, such as

HD 189733 b HD 189733 b is an exoplanet in the constellation of Vulpecula approximately away from the Solar System. Astronomers in France discovered the planet orbiting the star HD 189733 on October 5, 2005, by observing its transit across the star's face. ...

and

GJ 1214 b (sometimes , also named Enaiposha since 2023) is an exoplanet that orbits the star GJ 1214, discovered in December 2009. Its parent star is from the Sun, in the constellation Ophiuchus. At the time of its discovery, was the most likely kn ...

. NGTS is intended to greatly increase the number of planets that area analyzable using such techniques. Simulations of expected NGTS performance reveal the potential of discovering approximately 231 Neptune- and 39 super-Earth-sized planets amenable to detailed spectrographic analysis by the VLT, compared to only 21 Neptune- and 1 super-Earth-sized planets from the ''Kepler'' data.

Instrument

Development

The scientific goals of the NGTS require being able to detect transits with a precision of 1 mmag at 13th magnitude. Although at ground level this level of accuracy was routinely achievable in narrow-field observations of individual objects, it was unprecedented for a wide-field survey. To achieve this goal, the designers of the NGTS instruments drew upon an extensive hardware and software heritage from the WASP project, in addition to developing many refinements in prototype systems operating on La Palma during 2009 and 2010, and at the Geneva Observatory from 2012 to 2014.

Telescope array

NGTS employs an automated array of twelve 20-centimeter f/2.8 telescopes on independent equatorial mounts and operating at orange to near-infrared wavelengths (600–900 nm). It is located at the

European Southern Observatory The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental organization, intergovernmental research organisation made up of 16 m ...

in Chile, a location noted for low water-vapor and excellent photometric conditions.

Combined search

The NGTS telescope project cooperates closely with ESO's large telescopes. ESO facilities available for follow-up studies include the

High Accuracy Radial Velocity Planet Searcher The High Accuracy Radial Velocity Planet Searcher (HARPS) is a high-precision echelle planet-finding spectrograph installed in 2002 on the ESO's 3.6m telescope at La Silla Observatory in Chile. The first light was achieved in February 2003. ...

(HARPS) at

La Silla Observatory La Silla Observatory is an astronomical observatory in Chile with three telescopes built and operated by the European Southern Observatory (ESO). Several other telescopes are also located at the site and are partly maintained by ESO. The observato ...

;

for radial-velocity measurements at the VLT;

SPHERE A sphere (from Ancient Greek, Greek , ) is a surface (mathematics), surface analogous to the circle, a curve. In solid geometry, a sphere is the Locus (mathematics), set of points that are all at the same distance from a given point in three ...

, an adaptive optics system and coronagraphic facility at the VLT that directly images extrasolar planets; and a variety of other VLT and planned ELT instruments for atmospheric characterization.

Partnership

Although located at Paranal Observatory, NGTS is not in fact operated by ESO, but by a consortium of seven academic institutions from Chile, Germany, Switzerland, and the United Kingdom: * DLR, Institute for Planetary Research *

Queen's University Belfast The Queen's University of Belfast, commonly known as Queen's University Belfast (; abbreviated Queen's or QUB), is a public research university in Belfast, Northern Ireland, United Kingdom. The university received its charter in 1845 as part of ...

University of Cambridge The University of Cambridge is a Public university, public collegiate university, collegiate research university in Cambridge, England. Founded in 1209, the University of Cambridge is the List of oldest universities in continuous operation, wo ...

University of Chile The University of Chile () is a public university, public research university in Santiago, Chile. It was founded on November 19, 1842, and inaugurated on September 17, 1843.

University of Leicester The University of Leicester ( ) is a public university, public research university based in Leicester, England. The main campus is south of the city centre, adjacent to Victoria Park, Leicester, Victoria Park. The university's predecessor, Univ ...

University of Warwick The University of Warwick ( ; abbreviated as ''Warw.'' in post-nominal letters) is a public research university on the outskirts of Coventry between the West Midlands and Warwickshire, England. The university was founded in 1965 as part of ...

Results

* On 31 October 2017, the discovery of

NGTS-1b NGTS-1b is a confirmed hot Jupiter-sized extrasolar planet orbiting NGTS-1, a red dwarf star about half the mass and radius of the Sun, every 2.65 days. The NGTS-1 system is about 716 light-years from Earth in the Columba constellation. Discover ...

, a confirmed

hot Jupiter Hot Jupiters (sometimes called hot Saturns) are a class of gas giant exoplanets that are inferred to be physically similar to Jupiter (i.e. Jupiter analogue, Jupiter analogues) but that have very short orbital periods (). The close proximity to t ...

-sized

extrasolar planet An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first detect ...

orbiting NGTS-1, an M-dwarf star, about half the mass and radius of the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

, every 2.65 days, was reported by the survey team. Daniel Bayliss, of the

, and lead author of the study describing the discovery of NGTS-1b, stated, "The discovery of NGTS-1b was a complete surprise to us—such massive planets were not thought to exist around such small stars – importantly, our challenge now is to find out how common these types of planets are in the Galaxy, and with the new Next-Generation Transit Survey facility we are well-placed to do just that." * On 3 September 2018, the discovery of NGTS-4b, a sub-Neptune-sized planet transiting a 13th magnitude K-dwarf in a 1.34 day orbit. NGTS-4b has a mass 20.6 ± 3.0 and radius 3.18 ± 0.26 , which places it well within the so-called " Neptunian desert". The mean density of the planet (3.45 ± 0.95 g cm⁻³) is consistent with a composition of 100% H2O or a rocky core with a volatile envelope.

Discoveries

Planets

This is a list of planets discovered by this survey. This list is incomplete, and requires more information.

Brown dwarfs

In addition, the survey has discovered three brown dwarfs.

Notes

References

External links

* *
The Next Generation Transit Survey Becomes Operational at Paranal
ESO archive, The Messenger 165 – September 2016 {{Portal bar, Stars, Science Articles containing video clips Astronomical instruments Astronomical surveys European Southern Observatory Exoplanet search projects by small telescope Telescopes