The Westerbork Synthesis Radio Telescope (WSRT) is an

aperture synthesis Aperture synthesis or synthesis imaging is a type of interferometry that mixes signals from a collection of telescopes to produce images having the same angular resolution as an instrument the size of the entire collection. At each separation and ...

interferometer Interferometry is a technique which uses the '' interference'' of superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important investigative technique in the fields of astronomy, fiber opt ...

built on the site of the former World War II Nazi detention and transit camp Westerbork, north of the village of Westerbork,

Midden-Drenthe Midden-Drenthe () is a municipality in the northeastern Netherlands. The municipality was created in 1998, in a merger of the former municipalities of Beilen, Smilde, and Westerbork. Between 1998 and 2000, the name of the municipality was Middenve ...

, in the northeastern

Netherlands , Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...

Overview

The WSRT comprises fourteen radio telescopes deployed in a linear array arranged on a East-West line, of which 10 are in a fixed equidistant position, 2 are nearby on a rail track, and 2 are located eastwards on another rail track. It has a similar arrangement to other

radio telescope A radio telescope is a specialized antenna (radio), antenna and radio receiver used to detect radio waves from astronomical radio sources in the sky. Radio telescopes are the main observing instrument used in radio astronomy, which studies the r ...

s such as the

One-Mile Telescope The One-Mile Telescope at the Mullard Radio Astronomy Observatory (MRAO), Cambridge, UK is an array of radio telescopes (two fixed and one moveable, fully steerable parabolic reflectors operating simultaneously at 1407 MHz and 408 ...

Australia Telescope Compact Array The Australia Telescope Compact Array (ATCA) is a radio telescope operated by CSIRO at the Paul Wild Observatory, twenty five kilometres (16 mi) west of the town of Narrabri in New South Wales, Australia. Its opening ceremony took place on ...

and the

Ryle Telescope The Ryle Telescope (named after Martin Ryle, and formerly known as the 5-km Array) was a linear east-west radio telescope array at the Mullard Radio Astronomy Observatory. In 2004, three of the telescopes were moved to create a compact two-dime ...

. Its

Equatorial mount An equatorial mount is a mount for instruments that compensates for Earth's rotation by having one rotational axis, called ''polar axis'', parallel to the Earth's axis of rotation. This type of mount is used for astronomical telescope mount, tel ...

is what sets it apart from most other radio telescopes, most of which have an

Altazimuth mount An altazimuth mount or alt-azimuth mount is a simple two- axis mount for supporting and rotating an instrument about two perpendicular axes – one vertical and the other horizontal. Rotation about the vertical axis varies the azimuth (compass b ...

. This makes it specifically useful for specific types of science, like polarized emission research as the detectors maintain a constant orientation on the sky during an observation. Ten of the telescopes are on fixed mountings while the remaining two dishes are movable along two

rail tracks Railway track ( and UIC terminology) or railroad track (), also known as permanent way () or "P way" ( and Indian English), is the structure on a railway or railroad consisting of the rails, fasteners, sleepers ( railroad ties in American ...

. The telescope was completed in 1970 and underwent a major upgrade between 19952000. The telescopes in the array can operate at several frequencies between and with an instantaneous bandwidth of and 8092line spectral resolution. The WSRT is often combined with other telescopes around the world to perform

very-long-baseline interferometry Very-long-baseline interferometry (VLBI) is a type of astronomical interferometry used in radio astronomy. In VLBI a signal from an astronomical radio source, such as a quasar, is collected at multiple radio telescopes on Earth or in space. T ...

(VLBI) observations, being part of the

European VLBI Network The European VLBI Network (EVN) is a network of radio telescopes located primarily in Europe and Asia, with additional antennas in South Africa and Puerto Rico, which performs very high angular resolution observations of cosmic radio sources usin ...

. The telescope is operated by

ASTRON ASTRON is the Netherlands Institute for Radio Astronomy. Its main office is in Dwingeloo in the Dwingelderveld National Park in the province of Drenthe. ASTRON is part of the institutes organization of the Dutch Research Council (NWO). History A ...

, the Netherlands Institute for Radio Astronomy. WSRT performed a major upgrade in 2013 as part of the APERTIF (APERture Tile In Focus) project, where the current detectors were replaced with focal-plane arrays. The Telescope was out of operation for the upgrade from 2015 to 2019, which allows a 25x larger field of view. The upgraded telescope is used for large scale surveys of the northern sky, bringing back focus on the

Hydrogen line The hydrogen line, 21 centimeter line, or H I line is a spectral line that is created by a change in the energy state of solitary, electrically neutral hydrogen atoms. It is produced by a spin-flip transition, which means the dire ...

for which it was originally designed, but also large

pulsar A pulsar (''pulsating star, on the model of quasar'') is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its Poles of astronomical bodies#Magnetic poles, magnetic poles. This radiation can be obse ...

searches and other science. The WSRT is also an International

GNSS A satellite navigation or satnav system is a system that uses satellites to provide autonomous geopositioning. A satellite navigation system with global coverage is termed global navigation satellite system (GNSS). , four global systems are op ...

Service site. WSRT observed galaxies in the Spitzer Infrared Nearby Galaxies Survey at wavelengths of . The WSRT site is also hosting one of the two experimental EMBRACE (Electronic MultiBeam Radio Astronomy ConcEpt)

phased array In antenna (radio), antenna theory, a phased array usually means an electronically scanned array, a computer-controlled Antenna array, array of antennas which creates a radio beam, beam of radio waves that can be electronically steered to point ...

telescopes, part of the Phase 2 of the

Square Kilometre Array The Square Kilometre Array (SKA) is an intergovernmental organisation, intergovernmental international radio telescope project being built in Australia (low-frequency) and South Africa (mid-frequency). The combining infrastructure, the Square ...

(SKA) project.

References

External links

* {{Radio-astronomy Astronomical observatories in the Netherlands Buildings and structures in Drenthe Interferometric telescopes Midden-Drenthe Radio telescopes