Sloan Digital Sky Survey. Image Credit: Credit: SDSS Team, Fermilab Visual Media Services
The Sloan Digital Sky Survey, shortened SDSS, is major multi-filter imaging and spectroscopic redshift survey that uses a dedicated 2.5 m wide-angle optical telescope. It is located at Apache Point Observatory in New Mexico. The survey began in 2000 with the goal of mapping 25% of the sky and observe 100 million objects and the spectra of 1 million additional objects. The imaging survey has detected quasars beyond a redshift 6. In the year 2006 the survey entered a new phase, called SDSS-II, which aims to extend the observations and explore the structure and stellar makeup of the Milky Way.
The Sloan Digital Sky Survey uses its 2.5 m wide-angle optical telescope to take images using a photometric system of five filters. These images are processed to produce lists of objects observed, various parameters, and how the brightness relates to various kinds of astronomical magnitude. The telescope uses the drift scanning technique, so the telescope is fixed and makes use of the Earth’s rotation to record small strips of the sky. This method allows consistent astrometry over the widest possible field and precision remains unaffected by telescope tracking errors.
The telescope’s camera is made up of thirty charge-coupled device chips each with a resolution of 2048×2048 pixels. The chips are arranged in five rows of six chips. Each row has a different optical filter with wavelengths of 354, 476, 628, 769 and 925 nm up to a magnitude of 24.4, 25.3, 25.1, 24.4 and 22.9 with a signal to noise ratio of 5. To reduce noise the camera is cooled to 190 kelvin. The telescope is capable of recording 640 spectra at any one time by feeding an optical fiber for each through holes drilled in an aluminum plate. Every night the telescope produces about 200 gigs of data.
The Sloan Digital Sky Survey has discovered quasars at the limits of the observable universe, the distribution of galaxies, and the properties of stars in our galaxy. All of this information is freely shared on the survey’s website.
We have written many articles about the Sloan Digital Sky Survey for Universe Today. Here’s another article about the Sloan Digital Sky Survey, and here’s an article about futher evidence found for dark energy.
If you’d like more info on the Sloan Digital Sky Survey, check out the Official Website of the Sloan Digital Sky Survey, and here’s a link to Wikipedia’s article about the Sloan Digital Sky Survey.
We’ve also recorded an entire episode of Astronomy Cast all about Sky Surveys. Listen here, Episode 118: Sky Surveys.
Source: SDSS
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