The Narrabri Stellar Intensity Interferometer (NSII) was the first astronomical instrument to measure the diameters of a large number of

star A star is an astronomical object comprising a luminous spheroid of plasma held together by its gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night, but their immense distances from Earth make ...

s at visible wavelengths. It was designed by (amongst others)

Robert Hanbury Brown Robert Hanbury Brown, AC FRS (31 August 1916 – 16 January 2002) was a British astronomer and physicist born in Aruvankadu, India. He made notable contributions to the development of radar and later conducted pioneering work in the field of ...

, who received the

Hughes Medal The Hughes Medal is awarded by the Royal Society of London "in recognition of an original discovery in the physical sciences, particularly electricity and magnetism or their applications". Named after David E. Hughes, the medal is awarded with ...

in 1971 for this work. It was built by

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

School of Physics and was located near the town 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 Highwa ...

in north-central

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. Many of the components were constructed in the UK. The design was based on an earlier optical

intensity interferometer An intensity interferometer is the name given to devices that use the Hanbury Brown and Twiss effect. In astronomy, the most common use of such an astronomical interferometer is to determine the apparent angular diameter of a radio source or star ...

built by Hanbury Brown and

Richard Q. Twiss Richard Quintin Twiss (24 August 1920 – 20 May 2005) was a British astronomer. He is known for his work on the Hanbury-Brown and Twiss effect with Robert Hanbury Brown. It led to the development of the Hanbury Brown-Twiss intensity interfero ...

Jodrell Bank 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 astro ...

in the UK. Whilst the original device had a maximum baseline of 10m, the NSII device consisted of a large circular track that allowed the detectors to be separated from 10 to 188m. The NSII operated from 1963 until 1974, and was used to measure the angular diameters of 32 stars.

References

The angular diameters of 32 stars
Mon. Not. R. Astron. Soc. Volume 167 pp 121–136 (1974) * Hanbury Brown R, The intensity interferometer – its application to astronomy, Taylor & Francis, 1974 Telescopes Interferometric telescopes Science and technology in New South Wales Astronomical observatories in New South Wales {{NewSouthWales-stub

See also

References