An improved method for the determination of the orbital parameters of a binary system that contains a pulsating component

In this paper we present a method to assign statistical weights to radial-v elocity measurements of a binary system of which one of the components is a variable star. The basic idea of the method is to separate the radial-velo city changes due to the intrinsic variability from those due to the orbital motion. This can be achieved if part of the data set consists of good cove rages of the intrinsic variability cycle. These full coverages are used to estimate the variability for the nights on which only one or a few spectra were obtained. Our technique is applicable when the intrinsic variability h as a period that is considerably shorter than the orbital period. Once weights have been assigned, existing methods to derive the orbital par ameters can be used with better accuracy compared to the case where all dat a points are treated as if no intrinsic variability were present (equal wei ghts). We illustrate our method and compare the orbital solution obtained w ith and without assigning weights for three pulsating stars in a binary sys tem: beta Cru, epsilon Per, and kappa SCo.