Editing Ryle Telescope

{{Use dmy dates|date=April 2022}}
{{More citations needed|date=January 2024}}
{{Infobox telescope}}
[[File:cmglee Cambridge MRAO AMI Large Array.jpg|thumb|300px|The three AMI-LA antennas left of the hut in this June 2014 photograph were the ones moved in 2014]]

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]].<ref>{{Cite book |last=Pooley |first=Guy G. |url=https://ui.adsabs.harvard.edu/abs/2006smqw.confE..19P |title=Radio monitoring with the Ryle Telescope |date=2006-01-01|bibcode=2006smqw.confE..19P }}</ref> In 2004, three of the telescopes were moved to create a compact two-dimensional array of telescopes at the east end of the [[Interferometry|interferometer]]. The eight antennas have now become the [[Arcminute Microkelvin Imager]] Large Array.

== Design ==
The Ryle Telescope was an eight-element [[Interferometry|interferometer]] operating at [[Ku band|15 GHz (2cm wavelength)]]. The elements were equatorially mounted 13-m [[Cassegrain reflector|Cassegrain]] antennas, on an (almost) east-west baseline. Four aerials were mounted on a 1.2&nbsp;km [[Railway|rail track]], and the others were fixed at 1.2&nbsp;km intervals. Baselines between 18 m and 4.8&nbsp;km were therefore available, in a variety of configurations. For high-resolution imaging, the mobile aerials were arranged along the track, to give uniform baseline coverage to 4.8&nbsp;km; for low-brightness astronomy (e.g. the [[Sunyaev-Zel'dovich effect]]) the mobile aerials were arranged in a 'compact array', with a maximum baseline of about 100 m. All antenna pairs were correlated, so some long baseline data were always available, even in the 'compact array' configuration.

As the telescope was an east-west instrument, most imaging observations involved 12-hour observations in order to fill the [[Aperture synthesis|synthesised aperture]] ([[calibration]] observations are routinely interleaved). Another consequence of the geometry was that it is not practical to image sources near the [[equator]], or in the south. The two-dimensional Large Array overcomes this problem with its new north-south baselines.

Although the telescope was not designed as a common user instrument, the operators were happy to accept proposals for observing time on the instrument from outside observers, provided that they did not overlap substantially with existing observing programmes, on a 'best efforts' basis. Monitoring variable sources was possible using short observations which could often be inserted between longer 'standard' observations.

The telescope had three main scientific programs: study of the [[Sunyaev-Zel'dovich effect]] in [[Galaxy groups and clusters|galaxy clusters]], particularly in determining the [[Hubble constant]]; surveying for radio sources that would contaminate degree-scale [[Cosmic microwave background experiments|observations]] of the [[Cosmic microwave background radiation|cosmic microwave background]] made with the [[Very Small Array]], and flux monitoring of galactic variable sources.{{Citation needed|date=February 2025}}

== References ==
{{Reflist}}

[[Category:Radio telescopes]]
[[Category:Cavendish Laboratory]]
[[Category:Interferometric telescopes]]