  The Narrow-line Seyfert galaxy Ark 564 was monitored between June 04, 2000
and June 24, 2000 from Skinakas Observatory. The B,V,R and I band light curves
show night to night variations of 0.1 mag. Comparison with X-ray data from a
simultaneous ASCA observation shows that the X-ray variations are more
pronounced than in the optical band. Cross correlation analysis yields a time
lag of ~ 0.8 days in the sense that the X-rays are leading the optical but with
low statistical significance. We discuss possible implications of our results
to current physical models of AGN.
