Southern African Large Telescope

Southern African Large telescope

Alternative names	Southern African Large Telescope，SALT
Part of	South African Astronomical Observatory
Location(s)	Sutherland, Karoo Hoogland Local Municipality, Namakwa District Municipality, Northern Cape, RSA
Coordinates	32°22′34″S 20°48′38″E / 32.376005555556°S 20.810677777778°E / -32.376005555556; 20.810677777778
Observatory code	B31
Altitude	1,798 m (5,899 ft)[1]
Wavelength	320 nm (940 THz)–1,700 nm (180 THz)
Built	2005
Telescope style	optical telescope reflecting telescope segmented mirror
Diameter	hexagonal array of ~11.1 m × 9.8 m 9.2 m (effective aperture)
Angular resolution	EE(50) ≤ 0.6"
Collecting area	79 m2 (91 × 0.87 m2) 66.5 m2 (effective aperture)
Mounting	45 ton steel structure
Enclosure	25 m spherical
Website	www.salt.ac.za
Location of Southern African Large Telescope
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The Southern African Large Telescope (SALT) is a 9.2-metre optical telescope designed mainly for spectroscopy. It consists of 91 hexagonal mirror segments each with a 1-metre inscribed diameter, resulting in a total hexagonal mirror of 11.1 by 9.8 m.^[2] However, its effective aperture is only 9.2 m. It is located close to the town of Sutherland in the semi-desert region of the Karoo, South Africa. It is a facility of the South African Astronomical Observatory, the national optical observatory of South Africa.

SALT is the largest optical telescope in the southern hemisphere.^[3][4] It enables spectroscopic and polarimetric analysis and imaging of the radiation from astronomical objects that are out of reach of northern hemisphere telescopes.

It is closely based on the Hobby–Eberly Telescope (HET) at McDonald Observatory, with some changes in its design, especially to the spherical aberration corrector. The main purpose for these changes was to improve the telescope's field of view. It shares the same fixed mirror altitude design, which limits access to 70% of the visible sky.^[5]

First light with the full mirror was declared on 1 September 2005, with 1-arc-second resolution images of globular cluster 47 Tucanae, open cluster NGC 6152, spiral galaxy NGC 6744, and the Lagoon Nebula.^[6] The official opening by President Thabo Mbeki took place during the inauguration ceremony on 10 November 2005.^[7]

South Africa contributed about a third of the total of US$36 million that will finance SALT for its first 10 years (US$20 million for the construction of the telescope, US$6 million for instruments, and US$10 million for operations). The rest was contributed by the other partners: Germany, Poland, the United States, the United Kingdom, and New Zealand.^[8]