Context. Astrometry relies on the precise measurement of positions and motions of celestial objects. Driven by the ever-increasing accuracy of astrometric measurements, it is important to critically assess the maximum ...

Optical positions relative to the International Reference Stars Catalogue (IRS), and therefore in the system of the FK5, have been obtained for the optical counterparts of 40 compact extragalactic radio sources south of ...

Context. The solar-age open cluster M 67 (C0847+120, NGC 2682) is a touchstone in studies of the old Galactic disk. Despite its outstanding role, the census of cluster membership for M 67 at fainter magnitudes and their ...

Applying results from information and decision theory, in particular the Cram´er-Rao lower variance bound, we place limits on the maximum astrometric precision attainable by a CCD detector given the properties of the source, ...

Optical positions relative to the Hipparcos Catalogue (ESA 1997) have been obtained for the optical counterparts of 28 faint (B 20−23) southern compact extragalactic radio sources (CERS). Most of these sources are not ...