  We present a power spectrum analysis of the long ASCA observation of Ark 564
in June/July 2001. The observed power spectrum covers a frequency range of ~
3.5 decades. We detect a high frequency break at ~ 0.002 Hz. The power spectrum
has an rms of ~30% and a slope of ~ -1 and ~ -2 below and above the break
frequency. When combined with the results from a long RXTE observation (Pounds
et al. 2001), the observed power spectra of Ark 564 and Cyg X-1 (in the
low/hard state) are almost identical, showing a similar shape and rms
amplitude. However, the ratio of the high frequency breaks is very small (~
10e{3-4}), implying that these characteristic frequencies are not indicative of
the black hole mass. This result supports the idea of a small black hole
mass/high accretion rate in Ark 564.
