Two Planes of Satellites in the Centaurus A Group
  Tip of the red giant branch measurements based on Hubble Space Telescope and
ground-based imaging have resulted in accurate distances to 29 galaxies in the
nearby Centaurus A Group. All but two of the 29 galaxies lie in either of two
thin planes roughly parallel with the supergalactic equator. The planes are
only slightly tilted from the line-of-sight, leaving little ambiguity regarding
the morphology of the structure. The planes have characteristic r.m.s. long
axis dimensions of ~300 kpc and short axis dimensions of ~60 kpc, hence axial
ratios ~0.2, and are separated in the short axis direction by 303 kpc.
