By themselves, the 107 clusters for which data is given in the present
catalogue do not form a complete, volume-limited sample of 1 Abell clusters. However, the ENACS was designed to
establish, in combination with data available in the literature,
a database for a complete, "local" sample of
1 Abell
clusters with redshifts < 0.1. In Sect. 2.2 of Paper II, the resulting
complete sample of 128
1 clusters (with
0.1,
and in the solid angle defined by
and
) has been described.
For 78 of these clusters, data were provided exclusively by the ENACS,
while for 5 additional clusters the ENACS contributed to existing
data. As discussed in Paper II, these 128 clusters represent a total
of 158 10 clusters in a volume of 9.2 106 h
. One
of the results of the ENACS observations is that for 83 of the 128
clusters we have an improved estimate, through the redshifts, of the
contribution to the cluster richness from background galaxies.
In the ENACS cluster sample there is a general bias against clusters
with 0.04, as those are too extended for efficient
observation with the Optopus spectrograph. On the other hand, outside
the "cone" described above, we could not (and did not) seek to reach
completeness, and as a result clusters with
0.05 are
overrepresented in the ENACS, and for
0.06 the ENACS is only
complete within the "cone".
When selecting galaxy subsets from the ENACS catalogue it must always be remembered that, at the fainter magnitudes, galaxies without emission lines are significantly discriminated against in comparison with galaxies that have clear emission lines (see Sect. 2.5 of Paper III). As a result of the differences in the projected distributions of galaxies with and without emission lines, the application of a limit to the projected distance from the cluster centre influences the mix between early- and late-type galaxies (Sect. 5, ibid.).