Khác biệt giữa bản sửa đổi của “Khảo sát Bầu trời Kỹ thuật số Sloan”

Named after the [[Alfred P. Sloan|Alfred P. Sloan Foundation]], it aims to map 25% of the sky and obtain observations on around 100 million objects. It has [[redshift]]s for galaxies as far z=0.3 or 0.4, and has been involved in the detection of [[quasar]]s beyond a redshift 6.

 

SDSS uses a dedicated 2.5-m wide-angle optical telescope, and takes images through five filters (named u, g, r, i and z). These images are processed to produce lists of objects observed and various parameters, such as whether they seem pointlike or extended (as a galaxy might) and how the brightness on the [[Charge-coupled device|CCDs]] relates to various kinds of [[apparent magnitude|astronomical magnitude]].

 

Using this data targets are also selected for [[spectroscopy]]. The telescope is capable of recording 640 spectra at any one time by feeding an optical fibre for each through holes drilled in an aluminium plate. Each hole is individually positioned for the target in question.

 

To date there have been four data releases:

*The '''Early Data Release''' or '''EDR''' was released in June [[2001]] covering 462 square degrees and 53,000 spectra.

and 180 million photometrically-observed objects. [http://www.sdss.org/dr4]

 

The survey makes the data releases available over the Internet. The '''SkyServer''' provides a range of interfaces to an underlying [[Microsoft SQL database]]. Both spectra and images are available in this way, and interfaces are made very easy to use so that, for example, a full color image of any region of the sky covered by an SDSS data release can be obtained just by providing the coordinates. The SkyServer also provides a range of tutorials aimed at everyone from schoolchildren up to professional astronomers.

 

The raw data (from before it was processed into databases of objects) is also available through another Internet server.

 

 

Along with publications describing the survey itself, SDSS data has been used in publications over a huge range of astronomical topics. The SDSS website has a [http://www.sdss.org/publications/index.html full list] of these publications covering distant quasars at the limits of the observable universe, the distribution of galaxies, the properties of stars in our own galaxy and also subjects such as [[dark matter]] and [[dark energy]] in the universe. See also [[Sloan Great Wall]].

 

* [http://cas.sdss.org/ The SkyServer]

 

[[Category:Physical cosmology]]