Astron. Astrophys. Suppl. Ser. 135, 547-553

The multiperiodic $\delta$ Scuti star 4 Canum Venaticorum: 1997 APT photometry

M. Breger - F. Hiesberger

Send offprint request: M. Breger

Astronomisches Institut der Universität Wien, Türkenschanzstr. 17, A-1180 Wien, Austria e-mail: breger@astro.univie.ac.at

Received November 2; accepted November 30, 1998

Abstract:

204 hours of high-quality measurements of 4 CVn during 32 nights were obtained with the 0.75 m Automatic Photolectric Telescope (APT). The two comparison stars measured agreed to $\pm$2.7 mmag per single measurement in Stromgren y and $\pm$3.0 mmag in v. It is shown that APT's can be used successfully for the study of stellar nonradial pulsation at the millimag level.

An analysis of the multiperiodicity of 4 CVn revealed the presence of 19 simultaneously excited pulsation frequencies. This presents a considerable increase from the 7 frequencies found during a previous campaign of the Delta Scuti Network. The previously known frequencies were confirmed with amplitude variability on a time scale of years.

Key words: stars: $\delta$ Sct -- stars: oscillations -- stars: individual: 4 CVn -- techniques: photometric