Institut d'Astrophysique, Université de Liège, avenue de Cointe 5, B-4000 Liège, Belgium
2 Observatoire de Genève, CH-1290 Sauverny, Switzerland
Accepted: 12 May 1997
The photometric behaviour of 21 Ap stars has been analyzed from observations obtained in the Geneva system. Variability has been detected for 9 Ap stars, as well as for a star which initially was a comparison star. Preliminary values for the periods are presented as well as an analytical description of the light curves.
Key words: stars: chemically peculiar; variable
based on observations made at the Swiss telescope of the European Southern Observatory, La Silla, Chile.
Complete Table 4 is available in electronic form at the CDS via anonymous ftp 126.96.36.199 or http://cdsweb.u-strasbg.fr/Abstract.html and full figures are accessible on the on-line version of the paper.
© European Southern Observatory (ESO), 1998