Groups and clusters of galaxies in the SDSS DR8. Value-added catalogues
  Aims. We intend to compile a new galaxy group and cluster sample of the
latest available SDSS data, adding several parameter for the purpose of
studying the supercluster network, galaxy and group evolution, and their
connection to the surrounding environment.
  Methods. We used a modified friends-of-friends (FoF) method with a variable
linking length in the transverse and radial directions to eliminate selection
effects and to find reliably as many groups as possible. Using the galaxies as
a basis, we calculated the luminosity density field.
  Results. We create a new catalogue of groups and clusters for the SDSS data
release 8 sample. We find and add environmental parameters to our catalogue,
together with other galaxy parameters (e.g., morphology), missing from our
previous catalogues. We take into account various selection effects caused by a
magnitude limited galaxy sample. Our final sample contains 576493 galaxies and
77858 groups. The group catalogue is available at
http://www.aai.ee/~elmo/dr8groups/ and from the Strasbourg Astronomical Data
Center (CDS).
