Map of part of the night sky as
visible from the southern
hemisphere,
showing the location
of some of the
26,926
stars in the
Sydney southern
star
catalogue
A star as it appears on a
photographic glass plate used to
photograph the night sky
The branch of astronomy that measures the position and motion of objects in the sky is called astrometry and is derived from the Greek words astro (astron, meaning star) and meter (measure). From 1967 to 1983, astronomers at Sydney Observatory carried out an astrometry program to carefully measure the precise position and motion of about 80,000 stars visible from the southern hemisphere.
These astronomers took 1452 photographs of the night sky, using 20cm by 20cm photographic glass plates. Each photo was a six-minute exposure using a camera-like telescope with a 23cm wide lens. Great care was then taken to measure the precise position of the stars. In 1982, when only a third of the plates had been measured, the state government of the day decided to cease astronomical research at Sydney Observatory. In 1983, after a herculean effort, the unfinished catalogue was published as the Sydney Southern Star Catalogue (SSSC) by astronomers Dr David King and Dr Nick Lomb, in the Proceedings of the Royal Society of New South Wales (Volume 116, page 53). The catalogue, as published in 1983, contains 26,926 stars and would have included about 80,000 stars if all of the photographic plates had been measured.
