The Padova-Millennium Galaxy and Group Catalogue (PM2GC): the
  group-finding method and the PM2GC catalogues of group, binary and single
  field galaxies
  We present the construction and describe the properties of the
Padova-Millennium Galaxy and Group Catalogue (PM2GC), a galaxy catalogue
representative of the general field population in the local Universe. We
characterize galaxy environments by identifying galaxy groups at 0.04<=z<=0.1
with a Friends-of-Friends (FoF) algorithm using a complete sample of 3210
galaxies brighter than MB = -18.7 taken from the Millennium Galaxy Catalogue
(MGC, Liske et al. (2003)), a 38deg^2 photometric and spectroscopic equatorial
survey. We identified 176 groups with at least three members, comprising in
total 1057 galaxies and representing ~43 per cent of the general field
population in that redshift range. The median redshift and velocity dispersion
of our groups are 0.0823 and 192 km s^-1, respectively. 88 per cent of the
groups have fewer than ten members, and 63 per cent have fewer than five
members. Nongroup galaxies were subdivided into "inary" systems of two bright
close companions, and "single" galaxies with no companion, in order to identify
different environments useful for future scientific analysis. We performed a
detailed comparison with the 2PIGG catalogue to validate the effectiveness of
our method and the robustness of our results. Galaxy stellar masses are
computed for all PM2GC galaxies, and found to be in good agreement with Sloan
Digital Survey Data Release 7 (SDSS-DR7) mass estimates. The catalogues of
PM2GC groups, group properties and galaxy properties in all environments are
publicly available on theWorld Wide Web.
