... Zacharias, N. & Zacharias, M. I. 1999, in ASP Conf. ... The USNO CCD Astrograph Catalog South (UCAC-S) project is a high precision astrometric survey of the entire southern hemisphere for the 7 - 16 magnitude range, aiming at an accuracy of 20 mas for 8-14 m stars. ... The ACT (Urban et al. 1998) and the Hipparcos and Tycho Catalogues (ESA 1997) are used as reference (UCAC-R), supplemented by an extragalactic link program carried out in parallel mainly at the Cerro Tololo (CTIO) 0.9-meter telescope....