New spectroscopy of multiple stars RR Lyncis and HT Virginis

In this paper we present radial velocity measurements as a result of new spectroscopic observations of RR Lyncis and HT Virginis. Both systems are worth to be the objects of a long-term monitoring. The observations made during a long period of time reveal the apsidal motion and the movements around the center of mass of the systems. Long-term measurements enable us to measure the light-time effect in the eclipsing binaries as well. Data were collected using the Poznan Spectroscopic Telescope (PST1) at Borowiec station (Baranowski et al. 2009) covering a range of wavelength 4280-7500 Å. The telescope is equipped with an echelle spectrograph thermally stabilized to 0.1oC. The data were calibrated with ThAr (Thorium-Argon) lamp. Data reduction was performed with IRAF