Where to start

About the data

• The Early Data Release (EDR) paper (with a journal subscription, access the EDR paper at the AJ web site) is the most comprehensive printed description of SDSS data. Much of the information on this web site is based on the EDR paper. It should be considered essential reading to do science with SDSS data.
• However, some of the information in the EDR paper has been superseded by information on this web site. There is a description of changes from the Early Data Release to Data Release 1 (DR1) at the DR1 site (also see the DR1 paper Abazajian et al. 2003, AJ 126, 2081 (AJ site, subscription required); also at astro-ph/0305492).
• DR2: The DR2 paper (Abazajian et al. 2004, AJ, 128, 502 and astro-ph/0403325) contains the details, and the respective sections of this web site have been updated accordingly. The most important change is that the DR1 contained the "beta" processing of survey data. DR2 has bug-free photometry and vastly improved spectrophotometry -- see About DR2 on the DR2 site for details.
• About DR3 gives an overview of what DR3 contains, and a summary of the improvements in DR3 compared to earlier data releases. The DR3 paper (Abazajian et al. 2004, AJ 129, 1755) (available here as DR3.ps (2.6 MB)) gives a brief overview of the changes introduced in DR3.
• About DR4 briefly describes the contents of DR4, caveats for use of DR4 data, and upcoming features. There is also a DR4 paper (Adelman-McCarthy et al. 2006, ApJS 162, 38) (also available at astro-ph/0507711 and here as DR4.ps.gz, 326 KB).
• About DR5 describes the contents of DR5.

• These pages help to avoid the most common pitfalls in retrieving and using SDSS data:

  • When you use the photometric object catalogs, you must check the photometric object flags to obtain meaningful results.
  • When you use the spectroscopic catalogs, the photometric flag checking has been done as part of target selection. However, you must check the redshift status flag to exclude unsecure identifications and redshifts.
  • When you use the SQL database of the Catalog Archive Server (CAS), please read the advice on optimising CAS queries to avoid unnecessarily slow queries.

  Other caveats are detailed on the individual pages for each of our data products.

About SDSS

• The SDSS NASA proposal, which includes a detailed scientific justification, and comprehensive descriptions of the hardware.
• The York et al. technical summary paper of SDSS. You can access York et al. 2002 locally, as well as on astro-ph/0006396 and York et al. 2000 at the AJ web site (subscription required)
• The SDSS publication list, including
  • technical publications
  • scientific publications by members of the collaboration
  • publications based on SDSS data written by people outside the collaboration

This web site

Getting data

• DR4 sky coverage
• Data Products
• Data Access
• Tutorials for getting and using data
• Acknowledging the use of SDSS data
• Use IAU source designations of SDSS sources in publications

Documentation

• Survey instruments
• Data flow
• Algorithms
• Glossary of Terms