The Digital Sky Survey (DSS) is actually a collection of surveys covering various parts of the sky using ten different emulsion/filter combinations between 2950 and 9700 Angstrom. Some images have 1.0 arcsecond resolution and some 1.7 arcsecond resolution. SDSS has smaller pixels (0.39 arcsec) and uses narrower filters in five bands between 3551 Å and 8931 Å. 2MASS has 1 arcsecond pixels and used three near-infrared bands between 1.24 and 2.16 μm.
Coverage 2MASS and some of the DSS combination surveys are all-sky. SDSS DR6 covers 8420 square degrees, mostly in the north galactic polar region. For more information, see below.
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DSS
The photographic plates scanned for the Digitized Sky Survey were
taken through relatively wide spectral filters. None of the underlying datasets
are all-sky; the DSS "surveys" are actually composites of multiple image
sets taken at different times using different instruments. For more detailed
information on filters, dates, and coverage, see http://www-gsss.stsci.edu/SkySurveys/Surveys.htm Users should be aware that there is some overlap here. For instance, SERC-J (which covers much of the southern hemisphere) is used in both the composite surveys GSC1 and DSS2B. GSC2 is actually the same data as DSS2R. |
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| SDSS The Sloan Digital Sky Survey will map in detail one-quarters of the sky (concentrating on the north polar cap). Data Release 6 (DR6) covers 8420 square degrees. |
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2MASS
The Two Micron All-Sky Survey covers the whole sky in
three near-infrared bands. The user has a choice between the
nominal "single coverage" data and the "full survey" data which
goes much deeper in a few regions. See http://www.ipac.caltech.edu/2mass/releases/allsky/doc/seca2_2.html for more information. |
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