MERLIN

Last updated

e-MERLIN
MERLIN map.jpg
A map showing the locations of the antennas used in MERLIN
Alternative namesMERLIN OOjs UI icon edit-ltr-progressive.svg
Organization Jodrell Bank Observatory
University of Manchester   OOjs UI icon edit-ltr-progressive.svg
Location England
Website www.e-merlin.ac.uk OOjs UI icon edit-ltr-progressive.svg
TelescopesCambridge MERLIN telescope
Defford telescope
Knockin telescope
Pickmere telescope
Lovell Telescope
Mark II   OOjs UI icon edit-ltr-progressive.svg
  Commons-logo.svg Related media on Commons
[ edit on Wikidata]

The Multi-Element Radio Linked Interferometer Network (MERLIN) is an interferometer array of radio telescopes spread across England. The array is run from Jodrell Bank Observatory in Cheshire by the University of Manchester on behalf of Science and Technology Facilities Council (STFC). [1] [2] [3]

Contents

The array consists of up to seven radio telescopes and includes the Lovell Telescope at Jodrell Bank, Mark II, Cambridge, Defford in Worcestershire, Knockin in Shropshire, and Darnhall and Pickmere (previously known as Tabley) in Cheshire. [4] [5] The longest baseline is therefore 217 km and MERLIN can operate at frequencies between 151  MHz and 24  GHz. At a wavelength of 6 cm (5 GHz frequency), MERLIN has a resolution of 40 milliarcseconds which is comparable to that of the HST at optical wavelengths.[ citation needed ]

Some of the telescopes are occasionally used for European VLBI Network (EVN) and Very Long Baseline Interferometry (VLBI) observations in order to create an interferometer with even larger baselines, providing images with much greater angular resolution.

MTLRI

The radio telescope at Knockin Knockin Radio Telescope.jpg
The radio telescope at Knockin

In 1973, Henry Proctor Palmer made the suggestion of extending the interferometer links already in place at Jodrell Bank at the time, which started the planning of the telescope array. [6] [7] Construction started in 1975. [7] The system was originally officially called MTRLI (Multi-Telescope Radio Linked Interferometer), but was commonly referred to by the simpler name of MERLIN. It originally consisted of either the 76m Lovell Telescope or the 25m Mark II, along with the 25m Mark III at Wardle, the 85 ft at Defford and a new telescope at Knockin. This new telescope was made by E-Systems and was constructed based on the design for the telescopes in the Very Large Array, which was being constructed at the same time also by E-Systems. [8] [9]

The construction of the new telescope, the installation of microwave communication links and the construction of the correlator were jointly called "Phase 1" of the MERLIN project, the funding for which was approved on 30 May 1975. [10] The construction of the new telescope started on 9 July 1976, and was completed by 8 October 1976. The telescope was first controlled remotely from Jodrell in January 1977. [11] The microwave links were installed in May 1978. [12] The first observations using the system – measurements of 30 distant radio sources – were taken in January and February 1980. [13] The final cost of phase 1 of the system was £2,179,000 (1976). [13]

Two additional telescopes were added in Phase 2 of the project, along with their radio links to Jodrell Bank. While it was originally proposed that one of the telescopes would be sited at Jodrell Bank and the other at Darnhall, the pair were finally sited at Pickmere (also known as Tabley) and Darnhall. The two telescopes were the same as that at Knockin. Construction on both telescopes started on 9 April 1979, and was completed by 31 October 1979. The Pickmere telescope was connected into MTRLI for the first time on 20 July 1980, followed by the Darnhall telescope on 16 December 1980. The second phase was formally completed on the 31 December 1981, and had cost £3,142,210. [14]

The longest baseline of MTRLI was 134 km, between Pickmere and Defford. [8] The first map produced by the array was published on 6 November 1980. [7] In the first 2 years of operation (1980–1982), the array was used to observe at frequencies of 408 MHz (with a resolving power of 1  arcsecond), 1666 MHz (0.25 arcsecond) and 5 GHz (0.08 arcsecond). [15]

When the Mark II's surface was replaced in 1987, it could be used along with the three E-systems telescopes on the 22 GHz frequency, expanding MTRLI at that frequency. [8] One of the 18 m dishes of the One-Mile Telescope was temporarily used in MTRLI from 1987 until autumn 1990, which greatly improved its resolution. [16]

The Cambridge antenna in June 2014 Cmglee Cambridge MRAO MERLIN.jpg
The Cambridge antenna in June 2014

MTRLI was renamed to MERLIN in the early 1990s, and shortly afterwards the addition of the purpose-built 32 m Cambridge antenna in 1991 increased both the sensitivity and angular resolution of the array. The array also had a new correlator and new, cooled receivers, and some of the microwave links between the telescopes were improved so that the array could observe both hands of polarization. [17]

Since 1996, carousels for the different receivers on each of the E-systems telescopes and the Mark II telescope were installed (the Cambridge telescope already had such a system installed), providing frequency agility. In 1997 and 1998, dual-frequency (5 and 22 GHz) observations were made with the array for the first time. [17]

There are plans to construct a telescope in Ireland that would be added to the array. [18]

Original MTRLI telescopes
Name Coordinates
(links to map & photo sources)
Lovell Telescope 53°14′10.50″N02°18′25.74″W / 53.2362500°N 2.3071500°W / 53.2362500; -2.3071500 (Lovell Telescope)
Mark II 53°13′51.62″N02°18′34.16″W / 53.2310056°N 2.3094889°W / 53.2310056; -2.3094889 (Mark II)
Mark III 53°06′09.16″N02°31′15.63″W / 53.1025444°N 2.5210083°W / 53.1025444; -2.5210083 (Mark III) [19]
Defford 52°05′27.61″N02°08′09.62″W / 52.0910028°N 2.1360056°W / 52.0910028; -2.1360056 (Defford)
Knockin 52°47′23.9″N02°59′44.9″W / 52.789972°N 2.995806°W / 52.789972; -2.995806 (Knockin)
Pickmere 53°17′18.4″N02°26′38.4″W / 53.288444°N 2.444000°W / 53.288444; -2.444000 (Pickmere)
Darnhall 53°09′21.6″N02°32′03.3″W / 53.156000°N 2.534250°W / 53.156000; -2.534250 (Darnhall)
Current MERLIN telescopes
Name Coordinates
(links to map & photo sources)
Lovell Telescope 53°14′10.50″N02°18′25.74″W / 53.2362500°N 2.3071500°W / 53.2362500; -2.3071500 (Lovell Telescope)
Mark II 53°13′51.62″N02°18′34.16″W / 53.2310056°N 2.3094889°W / 53.2310056; -2.3094889 (Mark II)
Defford 52°05′27.61″N02°08′09.62″W / 52.0910028°N 2.1360056°W / 52.0910028; -2.1360056 (Defford)
Knockin 52°47′23.9″N02°59′44.9″W / 52.789972°N 2.995806°W / 52.789972; -2.995806 (Knockin)
Pickmere 53°17′18.4″N02°26′38.4″W / 53.288444°N 2.444000°W / 53.288444; -2.444000 (Pickmere)
Darnhall 53°09′21.6″N02°32′03.3″W / 53.156000°N 2.534250°W / 53.156000; -2.534250 (Darnhall)
Cambridge 52°10′1.2″N0°2′13.4″E / 52.167000°N 0.037056°E / 52.167000; 0.037056 (Cambridge)
Goonhilly [20] 50°02′53″N05°10′55″W / 50.04806°N 5.18194°W / 50.04806; -5.18194 (Arthur)

e-MERLIN

MERLIN used microwave links to send astronomical data back from the remote stations. These links had a limited bandwidth so much of the data was thrown away. In order to increase the sensitivity of the telescope the links were replaced by optical fibre links with a bandwidth of 4 GHz, compared to the original limit of 30 MHz, increasing the sensitivity of the array by a factor of around 30. This vast increase in data meant that the old correlator was no longer able to cope, so a new correlator was constructed which is capable of processing over 200 Gbit/s. [21]

Another major development which is part of the upgrade is frequency flexibility — the ability to alter the observing band of the entire array in a matter of minutes using rotating carousels of receivers. Some telescopes in the array already had this capability, while the rest required the visit of an engineer to change the receiver. When e-MERLIN becomes operational the telescope will be able to switch rapidly between 1.4, 5, 6 and 22 GHz. This is required in order to take advantage of optimum conditions for high frequency observations where atmospheric conditions can severely affect results.[ citation needed ]

Work started on the e-MERLIN upgrade in May 2004 and it was completed in 2009. [22] [23]

STFC's Programmatic Review 2007–08

On 6 March 2008 the Science and Technology Facilities Council (STFC) announced that the (e-MERLIN/JIVE) project was at risk because of a £80m shortfall in its budget. This was due to the initial recommendations of the Particle Physics, Astronomy and Nuclear Physics Science Committee (PPAN), that had listed the project as a "lower priority". Following concerns that PPAN's recommendations did not adequately represent the UK's astronomical priorities, [24] STFC established a wider consultation review involving various advisory panels to re-priorities the STFC program. [25] The Ground-Based Astronomy Consultation Panel then recommended e-MERLIN should be changed from the lowest band ("lower priority"), to the second highest, adding that "e-Merlin could be a world-leading facility well into the next decade" and "e-Merlin offered dramatic potential to both traditional UK radio astronomy users and importantly to a broader community". [26]

On 8 July 2008 STFC presented their final version of the programmatic review at a Town Meeting at the Royal Society stating: "Given the strategic importance of e-MERLIN to the future of UK radio astronomy and to the highly ranked SKA project, we are working with the University of Manchester and other stakeholders to find a viable way in which e-MERLIN operations can be supported in the medium term on a shared cost basis. We have made provision for STFC support of operations to be made available to facilitate such a solution." [27]

Scientific results

Among many other things, MERLIN has been used to observe:

The telescope can also be used for highly precise astrometry. [30] In 1998, MERLIN in conjunction with the Hubble Space Telescope discovered the first Einstein ring. [31] The telescope has also been used in combination with the VLA to carry out a weak lensing analysis. [32]

Related Research Articles

Radio telescope Directional radio antenna used in radio astronomy

A radio telescope is a specialized 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 radio frequency portion of the electromagnetic spectrum emitted by astronomical objects, just as optical telescopes are the main observing instrument used in traditional optical astronomy which studies the light wave portion of the spectrum coming from astronomical objects. Unlike optical telescopes, radio telescopes can be used in the daytime as well as at night.

Jodrell Bank Observatory Astronomical observatory in Cheshire, England

Jodrell Bank Observatory in Cheshire, England, hosts a number of radio telescopes as part of the Jodrell Bank Centre for Astrophysics at the University of Manchester. The observatory was established in 1945 by Bernard Lovell, a radio astronomer at the university, to investigate cosmic rays after his work on radar in the Second World War. It has since played an important role in the research of meteoroids, quasars, pulsars, masers and gravitational lenses, and was heavily involved with the tracking of space probes at the start of the Space Age.

Lovell Telescope Radio telescope at Jodrell Bank Observatory, Cheshire, England

The Lovell Telescope is a radio telescope at Jodrell Bank Observatory, near Goostrey, Cheshire in the north-west of England. When construction was finished in 1957, the telescope was the largest steerable dish radio telescope in the world at 76.2 m (250 ft) in diameter; it is now the third-largest, after the Green Bank telescope in West Virginia, United States, and the Effelsberg telescope in Germany. It was originally known as the "250 ft telescope" or the Radio Telescope at Jodrell Bank, before becoming the Mark I telescope around 1961 when future telescopes were being discussed. It was renamed to the Lovell Telescope in 1987 after Sir Bernard Lovell, and became a Grade I listed building in 1988. The telescope forms part of the MERLIN and European VLBI Network arrays of radio telescopes.

The Cavendish Astrophysics Group is based at the Cavendish Laboratory at the University of Cambridge. The group operates all of the telescopes at the Mullard Radio Astronomy Observatory except for the 32m MERLIN telescope, which is operated by Jodrell Bank.

Very Small Array Radio telescope in the Canary Islands

The Very Small Array (VSA) was a 14-element interferometric radio telescope operating between 26 and 36 GHz that is used to study the cosmic microwave background radiation. It was a collaboration between the University of Cambridge, University of Manchester and the Instituto de Astrofisica de Canarias (Tenerife), and was located at the Observatorio del Teide on Tenerife. The array was built at the Mullard Radio Astronomy Observatory by the Cavendish Astrophysics Group and Jodrell Bank Observatory, and was funded by PPARC. The design was strongly based on the Cosmic Anisotropy Telescope.

Submillimeter Array Astronomical radio interferometer in Hawaii, USA

The Submillimeter Array (SMA) consists of eight 6-meter (20 ft) diameter radio telescopes arranged as an interferometer for submillimeter wavelength observations. It is the first purpose-built submillimeter interferometer, constructed after successful interferometry experiments using the pre-existing 15-meter (49 ft) James Clerk Maxwell Telescope and 10.4-meter (34.1 ft) Caltech Submillimeter Observatory as an interferometer. All three of these observatories are located at Mauna Kea Observatory on Mauna Kea, Hawaii, and have been operated together as a ten element interferometer in the 230 and 345 GHz bands. The baseline lengths presently in use range from 16 to 508 meters. The radio frequencies accessible to this telescope range from 194–408 gigahertz (1.545–0.735 mm) which includes rotational transitions of dozens of molecular species as well as continuum emission from interstellar dust grains. Although the array is capable of operating both day and night, most of the observations take place at nighttime when the atmospheric phase stability is best.

Ryle Telescope

The Ryle Telescope 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-dimensional array of telescopes at the east end of the interferometer. The eight antennas have now become the Arcminute Microkelvin Imager Large Array.

European VLBI Network Network of radio telescopes across Europe that link together for radio interferometry

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 using very-long-baseline interferometry (VLBI). The EVN is the most sensitive VLBI array in the world, and the only one capable of real-time observations. The Joint Institute for VLBI ERIC (JIVE) acts as the central organisation in the EVN, providing both scientific user support and a correlator facility. Very Long Baseline Interferometry (VLBI) achieves ultra-high angular resolution and is a multi-disciplinary technique used in astronomy, geodesy and astrometry.

Astronomical interferometer Array used for astronomical observations

An astronomical interferometer or telescope array is a set of separate telescopes, mirror segments, or radio telescope antennas that work together as a single telescope to provide higher resolution images of astronomical objects such as stars, nebulas and galaxies by means of interferometry. The advantage of this technique is that it can theoretically produce images with the angular resolution of a huge telescope with an aperture equal to the separation between the component telescopes. The main drawback is that it does not collect as much light as the complete instrument's mirror. Thus it is mainly useful for fine resolution of more luminous astronomical objects, such as close binary stars. Another drawback is that the maximum angular size of a detectable emission source is limited by the minimum gap between detectors in the collector array.

Darnhall Human settlement in England

Darnhall is a civil parish and small village to the south west of Winsford in the Borough of Cheshire West and Chester and the ceremonial county of Cheshire in England. It had a population of 232 at the 2011 Census.

Mark II (radio telescope)

The Mark II is a radio telescope located at Jodrell Bank Observatory, near Goostrey, Cheshire, in the north-west of England. It was built on the site of the 218 ft (66.4 m) Transit Telescope. Construction was completed in 1964. The telescope's design was used as the basis of the 85 ft (26 m) Goonhilly 1 dish, and the Mark III telescope is also based on a similar design.

The Mark III was a portable and fully steerable radio telescope located at Wardle, near Nantwich, Cheshire in the north-west of England. Constructed in 1966, it was remotely controlled from Jodrell Bank Observatory, and was mainly used as part of the MERLIN radio telescope network. It was designed by Charles Husband at the instigation of Bernard Lovell.

This is a timeline of Jodrell Bank Observatory.

Defford Human settlement in England

Defford is a small village in the county of Worcestershire, England, located between the towns of Pershore and Upton-upon-Severn. It was once part of the Royal forest of Horewell. The woodlands were mostly removed around the time of the Civil War.

Jodrell Bank Centre for Astrophysics Astrophysics centre at the University of Manchester, England

The Jodrell Bank Centre for Astrophysics at the University of Manchester, is among the largest astrophysics groups in the UK. It includes the Jodrell Bank Observatory, the MERLIN/VLBI National Facility, and the Jodrell Bank Visitor Centre. The centre was formed after the merger of the Victoria University of Manchester and UMIST which brought two astronomy groups together. The Jodrell Bank site also hosts the headquarters of the SKA Observatory (SKAO) - the International Governmental Organisation (IGO) tasked with the delivery and operation of the Square Kilometre Array, created on the signing of the Rome Convention in 2019. The SKA will be the largest telescope in the world - construction is expected to start at the end of this decade.

Green Bank Interferometer

The Green Bank Interferometer (GBI) is a former radio astronomy telescope located at Green Bank, West Virginia (USA) and operated by the National Radio Astronomy Observatory (NRAO). It included three on-site radio telescopes of 85-foot (26m) diameter, designated 85-1, 85-3, and 85-2 and a portable telescope.

Pickmere Human settlement in England

Pickmere is a village and civil parish near Knutsford in the Borough of Cheshire East. It has a population of 541. Landmarks in and around the village include a lake, Pick Mere, at grid reference SJ682770.

Ian Morison

Ian Morison FRAS is an astronomer and astrophysicist who served as the 35th Gresham Professor of Astronomy.

Richard John Davis, OBE, FRAS was a radio astronomer for the Jodrell Bank Centre for Astrophysics at the University of Manchester.

Hydrogen Epoch of Reionization Array Low frequency radio telescope in South Africa

The Hydrogen Epoch of Reionization Array (HERA) is a radio telescope dedicated to observing large scale structure during and prior to the epoch of reionization. HERA is a Square Kilometre Array (SKA) precursor instrument, intended to observe the early universe and to assist in the design of the full SKA. Along with MeerKAT, also in South Africa, and two radio telescopes in Western Australia, the Australian SKA Pathfinder (ASKAP) and the Murchison Widefield Array (MWA), the HERA is one of four precursors to the final SKA. It is located in the Meerkat National Park.

References

  1. ↑ Davies, J. G.; et al. (1980). "The Jodrell Bank radio-linked interferometer network". Nature . 288 (5786): 64–66. Bibcode:1980Natur.288...64D. doi:10.1038/288064a0. S2CID   4338231.
  2. ↑ Lovell, Bernard (1985). The Jodrell Bank Telescopes. Oxford University Press. ISBN   0-19-858178-5.
  3. ↑ Bernard, Lovell (1990). Astronomer by Chance. London: Macmillan. ISBN   0-333-55195-8.
  4. ↑ Bahcall, J. N.; Kirhakos, S.; Schneider, D. P.; Davis, R. J.; Muxlow, T. W. B.; Garrington, S. T.; Conway, R. G.; Unwin, S. C. (1995). "Hubble Space Telescope and MERLIN Observations of the Jet in 3C 273". The Astrophysical Journal Letters. 452 (2): L91. arXiv: astro-ph/9509028 . Bibcode:1995ApJ...452L..91B. doi:10.1086/309717. ISSN   1538-4357. S2CID   118401963.
  5. ↑ Akujor, Chidi E.; Spencer, R. E.; Zhang, F. J.; Davis, R. J.; Browne, I. W. A.; Fanti, C. (1991). "MERLIN observations of steep-spectrum radio sources at 6 cm". Monthly Notices of the Royal Astronomical Society. 250 (1): 215–224. Bibcode:1991MNRAS.250..215A. doi: 10.1093/mnras/250.1.215 . ISSN   0035-8711.
  6. ↑ Lovell, Jodrell Bank Telescopes, p. 184
    Lovell, Astronomer by Chance, p. 312
  7. 1 2 3 Davies et al. (1980)
  8. 1 2 3 "JBO – MTRLI" . Retrieved 10 June 2007.
  9. ↑ Lovell, Jodrell Bank Telescopes, p. 185
  10. ↑ Lovell, Jodrell Bank Telescopes, p. 191
  11. ↑ Lovell, Jodrell Bank Telescopes, p. 201
  12. ↑ Lovell, Jodrell Bank Telescopes, p. 203
  13. 1 2 Lovell, Jodrell Bank Telescopes, p. 204
  14. ↑ Lovell, Jodrell Bank Telescopes, Chapter 20 (pp. 208–215)
  15. 1 2 Lovell, Jodrell Bank Telescopes, p. 220
  16. ↑ "MERLIN: The 32-metre Telescope". Merlin.ac.uk. Retrieved 17 August 2010.
  17. 1 2 "JBO – MERLIN" . Retrieved 10 June 2007.
  18. ↑ "Irish giant could get new partner". BBC News. 2 October 2000. Retrieved 6 April 2007.
    "A Radio Telescope for Ireland". Archived from the original on 7 April 2007. Retrieved 6 April 2007.
  19. ↑ "MERLIN user guide – 4.1 Location of Telescopes" . Retrieved 1 September 2010.
  20. ↑ "GHY-1 ARTHUR" . Retrieved 12 December 2019.
  21. ↑ "'Superscope' yields first glimpse of Double Quasar". BBC. 10 December 2010.
  22. ↑ Healy, F.; O'Brien, T. J.; Beswick, R. (2016). "eMERLIN imaging of γ-ray nova V959 Mon's surprising evolution". Journal of Physics: Conference Series. 728 (4): 042002. Bibcode:2016JPhCS.728d2002H. doi: 10.1088/1742-6596/728/4/042002 . ISSN   1742-6588.
  23. ↑ "Giant UK telescope gets upgrade". BBC News. 26 May 2004. Retrieved 5 April 2007.
  24. ↑ Smith, Lewis (12 March 2008). "Jodrell Bank to close because scientists voted for own plans". The Times. London. Retrieved 12 May 2010.
  25. ↑ "STFC Consultation - Comment". Archived from the original on 2 August 2008. Retrieved 15 August 2008.
  26. ↑ "Archived copy" (PDF). Archived from the original (PDF) on 27 February 2009. Retrieved 15 August 2008.{{cite web}}: CS1 maint: archived copy as title (link)
  27. ↑ "Archived copy" (PDF). Archived from the original (PDF) on 27 February 2009. Retrieved 12 April 2009.{{cite web}}: CS1 maint: archived copy as title (link)
  28. ↑ Lovell, Jodrell Bank Telescopes, p. 221
  29. ↑ Lovell, Jodrell Bank Telescopes, p. 224
  30. ↑ Lovell, Jodrell Bank Telescopes, p. 226
  31. ↑ "A Bull's Eye for MERLIN and the Hubble" . Retrieved 10 June 2007.
  32. ↑ Patel, P.; Bacon, D. J.; Beswick, R. J.; Muxlow, T. W. B.; Hoyle, B. (2010). "Radio weak gravitational lensing with VLA and MERLIN". Monthly Notices of the Royal Astronomical Society . 401 (4): 2572. arXiv: 0907.5156 . Bibcode:2010MNRAS.401.2572P. doi:10.1111/j.1365-2966.2009.15836.x. S2CID   55876431.
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