  We are engaged in an investigation of the relationship between the properties
of BCG candidates and X-ray characteristics of their host clusters for a
flux-limited sample of ~250 ACO clusters from the ROSAT all-sky survey. We aim
to search for the convergence scale of bulk streaming flows within the ~300 Mpc
defined by this sample. X-ray selection provides significant advantages over
previous optically selected samples. No R-band magnitude-structure correlation
is present in this sample. Furthermore, no correlation between R-band magnitude
of the BCG candidate and X-ray luminosity of the host cluster is evident. The
resultant scatter of 0.34 mag. is larger than in (corrected) optically selected
samples. Hence, attempts to recover Local Group peculiar velocity vectors with
respect to inertial frames defined by such samples via standard candle methods
may have limited sensitivity.
