  We explore the angular distribution of two samples of satellite galaxies
orbiting isolated hosts extracted from the Sloan Digital Sky Survey Data
Release 4. We find a clear alignment of the satellites along the major axis of
their hosts when restricting the analysis to red hosts. The anisotropy is most
pronounced for red satellites of red hosts. We find that the distribution of
the satellites about blue, isolated hosts is consistent with isotropy. We show
that under the assumption that the true, underlying distribution of satellites
of blue hosts exhibits the same anisotropy as the satellites of red hosts, the
sample of blue hosts is too small to measure this anisotropy at a
statistically-significant level. The anisotropy that we detect for satellites
about red primaries is independent of the projected radius. In particular, it
is evident at large projected distances from primaries (300 < r_p < 500 kpc).

Astrophysics