  The "dark flow" dipole is a statistically significant dipole found at the
position of galaxy clusters in filtered maps of Cosmic Microwave Background
(CMB) temperature anisotropies. The dipole measured in WMAP 3, 5 and 7 yr data
releases was 1) mutually consistent, 2) roughly aligned with the all-sky CMB
dipole and 3) correlated with clusters' X-ray luminosity. We analyzed WMAP 9 yr
and the 1st yr Planck data releases using a catalog of 980 clusters outside the
Kp0 mask to test our earlier findings. The dipoles measured on these new data
sets are fully compatible with our earlier estimates, being similar in
amplitude and direction to our previous results and in disagreement with the
results of an earlier study by the Planck Collaboration. Further, in Planck
datasets dipoles are found independent of frequency, ruling out the Thermal
Sunyaev-Zeldovich as the source of the effect. Both, in WMAP and Planck, we
find a clear correlation between the dipole measured at the cluster location in
filtered maps with the average anisotropy on the original maps, further proving
that the dipole is associated with clusters. The dipole signal is dominated by
the most massive clusters, with a statistical significance better than 99\%,
slightly larger than in WMAP. Since both data sets differ in foreground
contributions, instrumental noise and other systematics, the agreement between
WMAP and Planck dipoles argues against them being due to systematic effects in
either of the experiments.
