ET And, HD 219891, or HD 219668 - which one shows short-term variability?

The result of recent photometric observations of the CP star ET And, publis hed by Weiss et al. (1998), shows that the known brightness variation of ab out 145 min has to be obviously assigned to the comparison star HD 219891. In order to test this statement we investigate the Hipparcos photometry of ET And, HD 219891 and the check star, HD 219668, on the existence of pulsat ions. The significance of peaks found in the periodograms is estimated usin g empirically determined false alarm probability distributions derived from a large number of synthetic data sets. Results show that the probability o f large peaks produced in the periodograms by only noise cannot be describe d by the well-known statistics valid for an evenly spaced time sampling. In the photometry of ET And we find a period of 0(d).103966 with a false alar m probability of 6% or less. For the two comparison stars we could not dete ct any signal in the data.