SALT first light

Africa's largest telescope, SALT, had its Inauguration on Thursday when it was officially opened by the South African President Thabo Mbeki. SALT is an 11-m telescope constructed from 91 separate hexagonal mirror segments and is based on a similar design to the Hobby-Eberly telescope in the USA. The design is very unusual for an optical telescope as it doesn't drive in Right Ascension and Declination but rotates in azimuth as most radio telescopes do. However it doesn't tip in elevation. This might make you wonder how it can track an object on the sky. Well, rather than tip the main mirror - which would deform because of gravity - it moves the instruments (e.g. camera) to compensate. In effect the eyepiece moves while the telescope stays still.

The South African Large Telescope at the South Africa Astronomical Observatory, Sutherland, South Africa CREDIT: Stuart

SALT tea room
The tearoom at SALT, SAAO CREDIT: Stuart
I was lucky enough to visit the South Africa Astronomical Observatory a couple of years back and I got a tour around SALT as it was being built by an international team of engineers. At that time there were only a few mirrors in place but it still looked pretty impressive. In the image above, SALT is inside the big shiny dome with the column next to it. The top of the tower sits at the centre of curvature of the main mirror and every so often they use this to check the shape of the mirror. The air conditioning and various utilities are in the short building to the left.

The telescope dome itself is pretty huge and has plenty of rooms. There is a main control room with a viewing gallery so the public can make funny faces at the engineers and astronomers on duty. If you have ever spent a night observing you will know that it often gets cold and, to keep awake, astronomers drink copious amounts of tea or coffee. I am glad to say that the dome has its very own tea room (see my sneaky picture to the left).

Back at the start of September SALT released the first light images. They aren't the best images ever taken, as there seem to be some issues with matching up the images taken with different colours filters, but they are the first with a new telescope so they will improve. I can't wait to see more.

47 Tuc
SALT first light image showing globular star cluster 47 Tucane located about 15000 light years away. CREDIT: SALT

Posted in astro blog by Stuart on Saturday 12th Nov 2005 (23:20 UTC) | Permalink
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