Current Science at NOAO
SOAR 4m Telescope
Stan Hart, NOAO RET
June, 2000 | The primary mirror blank for the SOAR (SOuthern Astrophysical Research) 4m Telescope has been completed at Corning's Canton, New York, plant. A mirror blank is a curved piece of glass, to which a reflective coating of aluminum will be added, so that the surface will reflect light from distant stars. The primary mirror is the largest mirror in a reflecting telescope. It's also where the light first strikes and the rays bent so that they can be focused into an image. The SOAR mirror blank is made of a special type of ULE (ultra low expansion) glass, which will allow astronomers to get clearer images with less distortion caused by temperature changes.
From Canton, the mirror will go to Raytheon in Danbury Connecticut, for polishing and finishing. When finished the glass blank will be shipped to Cerro Pachón, Chile, where the telescope is being constructed. There are several telescopes on a mountaintop there, far from any city lights, which interfere with astronomers' observations. Telescopes are built on mountaintops because the cooler and thinner air at higher elevations is easier for light from distant stars to pass through without being distorted. The construction of one of these big telescopes takes a long time because all the work must follow exacting specifications. Plus the mechanism that is required to precisely aim a large mirror weighing several tons is quite large itself. Everything must be checked and rechecked at every step along the way. The projected completion date for the SOAR telescope is mid 2003 when routine scientific observations will begin.
When completed, the SOAR telescope will join the Gemini South 8m telescope which is now undergoing final testing. The two telescopes will complement and supplement each other in observing images and spectra of distant stars and other astronomical objects. Of particular interest to astronomers is observing the infrared region of the electromagnetic spectrum of distant stars and galaxies. Part of the instrument package for the SOAR telescope includes a near infrared, intermediate-resolution spectrometer specifically for this purpose
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