RADIAL-VELOCITY CURVES FOR RR LYRAE STARS IN THE GLOBULAR CLUSTER-M5 AND CLUSTER-M92 OBTAINED USING SYNTHETIC SPECTRA CROSS-CORRELATION TEMPLATES

Radial-velocity curves are presented for the RR Lyrae stars V1 and V3 in the low-metallicity globular cluster M92 (NGC 6341) and V8 and V28 in the intermediate-metallicity globular cluster M5 (NGC 5904) based o n between 50 and 90 observations per star. The radial velocities were derived by cross-correlating spectra obtained with the Multiple Mirror Telescope echelle spectrograph with synthetic templates calculated us ing Kurucz's model atmospheres (ATLAS8) and synthetic spectrum (SYNTHE ) codes. The synthetic templates provide a better match to the observe d spectra than the available observed templates, especially for the me tal-poor stars, resulting in high-precision radial velocities good to a few km s-1 in most cases. We find systemic velocities of -125.4, -12 2.6, +48.7, and +53.6 km s-1 for M92-V1, M92-V3, M5-V8, and M5-V28, re spectively, in good agreement with previous determinations of cluster mean velocities.