1 Introduction

This series of papers is dedicated to the study of galaxy coordinates. In a first paper (Paturel & Petit 1999; Paper I) we calculated the mean error in right ascension (RA also designated as $\alpha$) and declination (DEC also designated as $\delta$) for the largest catalogues of galaxies. This was a preliminary step allowing us to judge the quality of individual catalogues. This is particularly important for cross-identifying new galaxies with galaxies catalogued many years ago. For instance, let us consider a new galaxy with good coordinates (say with a mean error of a few arcseconds). If it is cross-checked with a galaxy which has only coordinates from e.g. the Morphological Catalogue of Galaxies (MCG, Vorontsov-Velyaminov et al. 1963), for which we know that the mean error is 77 arcsec (Paper I), then a discrepancy of about 3 arcmin is acceptable at the 2-$\sigma$ level. On the other hand, if it does not match a galaxy measured by Shectman et al. (1996) or Klemola et al. (1994) within about 5 arcsec, the identity of the galaxies cannot be accepted.

This knowledge is particularly important when we are managing large galaxy samples, as we are regularly doing with LEDA or HYPERCAT databases (for more information about these databases see http://www-obs.univ-lyon1.fr). The problem becomes crucial when we try to cross-check galaxies from different databases or when we intend to cross-identify more than one million of galaxies in an automatic process.

Unfortunately, many galaxies have not yet received accurate measurement of their coordinates. This pressing need for accurate coordinates has led some groups to measure positions for their own work. Examples include Condon et al. (1982), Schneider et al. (1990), Giovanelli & Haynes (1993) and Corwin et al. (1998). In this paper we use the tools developed in HYPERCAT to measure coordinates from images of the Digitized Sky Survey (DSS). These images were retrieved from the http server of the European Southern Observatory in Münich.

In Sect. 2 we describe the process of measurement. In Sect. 3, we make an evaluation of the external accuracy. In Sect. 4 we give the results for a list of galaxies extracted from the LEDA database. The tables are presented but only a short part of them are printed. The entire tables are available in electronic form via the CDS archives.