CROSS-CORRELATION RADIAL-VELOCITY TECHNIQUES FOR ROTATING F-STARS

Data reduction techniques for cross-correlation determination of radia l velocities for F stars using echelle spectra obtained with the Cente r for Astrophysics Digital Speedometers are described and evaluated. S ynthetic spectra, calculated for a grid of spectral types and rotation al velocities, are used to derive radial velocities for a large sample of nearby F stars with a wide range of rotational velocities. Using a grid of calculated spectra provides a set of noise-free templates on a consistent wavelength scale and allows a closer match between the ro tational velocity of the object and that of the template spectrum than would be possible using observed spectra as templates. We describe th e methods used to choose the template parameters for each star and the tests conducted to evaluate the accuracy of our procedure. Typically the random error of a single velocity measurement is in the range 0.7 to 3 km s-1, depending primarily on the rotation of the star. The zero point of our velocity system has been established to an accuracy of b etter than 1 km s-1 for the F stars.