UK Schmidt Telescope

The 1.2 metre UK Schmidt Telescope (UKST) is operated by the Australian Astronomical Observatory (formerly the Anglo-Australian Observatory), and located adjacent to the 3.9 metre Anglo-Australian Telescope at Siding Spring Observatory, Australia. It is very similar to the Samuel Oschin telescope in California. The telescope can detect objects down to magnitude 21 after an hour of exposure on photographic plates.

It was originally built and operated by the United Kingdom, opening in 1973, then merged with the former Anglo-Australian Observatory in 1988; since the UK withdrew from the AAO in 2010 it has been wholly operated by Australia (though the name is unchanged).

The UKST is a Schmidt camera, with a design based on the Oschin Schmidt Telescope. It is a survey telescope with a 6° by 6° field of view, originally imaged onto a 35cm square glass photographic plate, and was the primary source of optical survey data in the southern sky from the 1970s to after 2000. The original sky survey plates were digitally scanned by the Space Telescope Science Institute to create the Guide Star Catalog for the Hubble Space Telescope, and the Digitized Sky Survey.

Schmidt camera

A Schmidt camera, also referred to as the Schmidt telescope, is a catadioptric astrophotographic telescope designed to provide wide fields of view with limited aberrations. The design was invented by Bernhard Schmidt in 1930.

Some notable examples are the Samuel Oschin telescope (formerly Palomar Schmidt), the UK Schmidt Telescope and the ESO Schmidt; these provided the major source of all-sky photographic imaging from 1950 until 2000, when electronic detectors took over. A recent example is the Kepler spacecraft exoplanet finder.

Other related designs are the Wright Camera and Lurie–Houghton telescope.

Invention and design

The Schmidt camera was invented by German-Estonian optician Bernhard Schmidt in 1930. Its optical components are an easy-to-make spherical primary mirror, and an aspherical correcting lens, known as a Schmidt corrector plate, located at the center of curvature of the primary mirror. The film or other detector is placed inside the camera, at the prime focus. The design is noted for allowing very fast focal ratios, while controlling coma and astigmatism.