Online Telescope, Information Database, and More
In my last article I wrote about online telescopes that allow users to control telescopes from their personal computers. Most of these allow users to actually control a telescope in real time or to schedule images in a queue. Some of these were not real telescopes at all, though; they are collections of images that users can request as if they are directing a telescope. The Sloan Digital Sky Survey's (SDSS) SkyServer is such a great resource because it can be used as such, but also gives users a large variety of options for requesting data.
The SDSS website states that their goal is to "map one-quarter of the entire sky and perform a redshift survey of galaxies, quasars and stars." In simpler terms, they collected images and information on a large portion of sky and organized it into a database. Information was gathered and compiled in multiple releases, the most recent and final being "Data Release 7" (DR7). SkyServer is a collection of tools allowing users to retrieve images and other data from their publicly accessible catalogue of more than 350 million celestial objects, and spectra of 30,000 galaxies, 120,000 quasars, and 460,000 stars.
The data comes from three surveys, named Legacy, SEGUE (Sloan Extension for Galactic Understanding and Exploration), and Supernova. Legacy is a five-band image survey over 8,423 square degrees of the sky in the Northern and Southern Galactic Caps, as well as spectroscopy of complete samples of galaxies and quasars. SEGUE includes images of additional areas of sky at lower galactic latitudes and spectroscopy of 240,000 stars from both the Legacy and SEGUE footprints. These images are used to study the structure of the Milky Way. Images in Supernova are the equivalent of 80 repeated redshift imaging scans of the Southern Equatorial Stripe, which are used to search for supernovae.