Variable stars: Which Nyquist frequency?

Observatoire de Genève, CH-1290 Sauverny, Suisse

Send offprint request to: L. Eyer

Received: 27 April 1998
Accepted: 24 August 1998

Abstract

In the analysis of variable stars, the problem of sampling is central. This article focusses on the determination of the Nyquist frequency. It is well defined in the case of regular sampling. However, the time series of variable stars observations are generally unevenly sampled. Fourier analysis using the spectral window furnishes some clues about the equivalent Nyquist frequency in the irregular case. Often it is pushed very high, and thus very short periods can be detected. A specific example is shown, drawn from MACHO databases.