High‐Precision Radial Velocity Measurements of Some Southern Stars

Abstract

ABSTRACTPrecise absolute radial velocities have been obtained at Mount John University Observatory for a number of southern stars, using the 1 m telescope and fiber‐fed echelle spectrograph. Only the stars that have been observed three or more times are presented, including 14 IAU standards and 11 program stars. Six echelle orders in the green (5000–5600 Å) are used. Many delicate steps have been undertaken in order to maintain the same conditions in both recording and reducing the spectra over a period of 27 months. The Th‐Ar lamp has been used for the wavelength calibration. The absolute radial velocities have been determined by cross‐correlation with synthetic spectra computed by R. L. Kurucz. The zero point has been adjusted using blue‐sky spectra. An additional strong correlation, between the measured velocities and photon counts in stellar and Th‐Ar spectra, has been detected for the PM3000 CCD camera and has been eliminated. A resulting precision of about 20–30 m s−1 has been obtained. The overall uncertainty of the absolute radial velocities was estimated to be about 100–200 m s−1. The present paper is a continuation of our recent previous work, including more details on the reduction process and the presentation of the radial velocities for more stars.