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
About DR3 gives
an overview of what DR3 contains, and a summary of the
improvements in DR3 compared to earlier data releases. The DR3
et al. 2004, AJ 129, 1755) (available here as DR3.ps (2.6 MB))
gives a brief overview of the changes introduced in DR3.
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.