Cavendish Astrophysics Group

Aperture Masking Interferometry is a form of speckle interferometry, allowing diffraction limited imaging from ground based telescopes. This technique allows ground based telescopes to reach the maximum possible resolution, allowing ground-based telescopes with large diameters to produce far sharper images than the Hubble Space Telescope. The principle limitation of the technique is that it is limited to relatively bright astronomical objects. A mask is placed over the telescope which only allows light through a small number of holes. ...

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Read more here: » Aperture Masking Interferometry: Encyclopedia - Aperture Masking Interferometry

9C The Ninth Cambridge Catalog of Radio Sources (9C) is an astronomical catalogue of celestial radio sources as measured at 15-GHz. It was published in 2003 by the Cavendish Astrophysics Group of the University of Cambridge. The catalogue was originally made in order to locate radio sources which were interfering with observations using the Very Small Array, but the catalogue has also proved useful for other astronomical programs. Sources are labelled 9CJHHMM+DDMM where HHMM+DDMM are the coordinates in the J2000 system, e.g. 9CJ1510+4138. < ...

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Later, optical interferometry was used on the Mount Wilson Observatory's reflector telescope in order to measure the diameters of stars. This method was extended to measurements using separated telescopes by Johnson, Betz and Towns (1974) in the infrared and by Labeyrie (1975) in the visible. The red giant star Betelgeuse was among the first to have its diameter determined in this way. In the 1980s the aperture synthesis technique was extended to visible light and infrared astronomy by the Cavendish Astrophysics Group, providing the first ve ...

See also:

Optical interferometry, Optical interferometry - Astronomical optical interferometry, Optical interferometry - For further information see, Optical interferometry - The Michelson-Morley experiment, Optical interferometry - Geodetic standard baseline measurements, Optical interferometry - Holography, Optical interferometry - Inertial navigation

Read more here: » Optical interferometry: Encyclopedia II - Optical interferometry - Astronomical optical interferometry

A famous use of white light interferometry is the precise measurement of geodetic standard baselines as invented by Yrjö Väisälä. Here, the light path is split in two, and one leg is "folded" between a mirror pair 1 m apart. The other leg bounces once off a mirror 6 m away. Only if the second path is precisely 6 times the first, will fringes be seen. Starting from a standard quartz gauge of 1 m length, it is possible to measure distances up to 864 m by repeated multiplication. Baselines thus established are used to calibrate geodetic distance measurement equipment on, leading to a m ...

See also:

Optical interferometry, Optical interferometry - Astronomical optical interferometry, Optical interferometry - For further information see, Optical interferometry - The Michelson-Morley experiment, Optical interferometry - Geodetic standard baseline measurements, Optical interferometry - Holography, Optical interferometry - Inertial navigation

Read more here: » Optical interferometry: Encyclopedia II - Optical interferometry - Geodetic standard baseline measurements