Sydney University Stellar Interferometer

The Sydney University Stellar Interferometer (SUSI) was an optical long baseline

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 op ...

owned by The

University of Sydney The University of Sydney (USYD), also known as Sydney University, or informally Sydney Uni, is a public research university located in Sydney, Australia. Founded in 1850, it is the oldest university in Australia and is one of the country's si ...

. It was located in the

Paul Wild Observatory The Paul Wild Observatory, also known as the Narrabri Observatory and Culgoora Observatory, is an astronomical research facility located about 24 km west of Narrabri, New South Wales, Australia. It is the home of the Australia Telescope Compa ...

, 20 km west of

Narrabri Narrabri ( ) is a locality and seat of Narrabri Shire local government area in the North West Slopes, New South Wales, Australia on the Namoi River, northwest of Sydney. It sits on the junction of the Kamilaroi Highway and the Newell Highway. At ...

town in

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

. The

had several siderostats, which collected and reflected starlight into the optical laboratory for interferometry via two vacuum pipes. Although mirrors at the siderostats were 20 cm in diameter, the effective aperture size was 14 cm as they operated at angles of about 45°. By selecting the different siderostats at different distances, the baseline of the interferometer could be varied between 5m and 640m. With beam-combining instruments that operated at visible wavelengths (~550-850 nm), SUSI had an

angular resolution Angular resolution describes the ability of any image-forming device such as an optical or radio telescope, a microscope, a camera, or an eye, to distinguish small details of an object, thereby making it a major determinant of image resolution. ...

of up to ~0.7mas (

milliarcseconds A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The n ...

). {{observatory-stub Interferometers Optical telescopes