POSSIBILITY OF DETERMINING STELLAR RADIAL-VELOCITIES TO O.OIKM S-1

Dissimilarities in the illumination of spectrographs by star light and by comparison sources, respectively, normally prevent the realization of radial-velocity accuracies anywhere near those which high-resolution spectrographs ought to provide. These difficulties can be entirely circumvented by the use of telluric absorption lines as the stationary comparison source. There seems to be no reason, if the appropriate and possible precautions enumerated in this paper are taken, why radial velocities accurate to 10 m s_1 should not be achieved for a restricted selection of stars. Existing spectrograms, taken for other purposes and without the benefit of any special precautions, already show an accuracy well in advance of normal standards. © Royal Astronomical Society.