A search for photometric variability in the central star of NGC 6543

We present intermediate-band CCD observations of HD 164963, the central star of the planetary nebula NGC 6543. The observations were obtained on four nights spread over an interval of approximately a year with the 0.9-m James Gregory Telescope and CCD camera, employing an intermediate-band continuum filter (⁠|λ_ c = 5300| Å). They show no evidence for photometric variability of the central star on a time-scale similar to that suggested by the radial-velocity variations found by Acker at a level greater than 0.04 mag, despite the fact that it is known to exhibit spectral variations at both optical and ultraviolet wavelengths. These observations suggest that HD 164963 is a member of the recently identified class of objects known as ‘wind variables’.