A catalog of isolated galaxy pairs with accurate radial velocities

Abstract

The present paper is devoted to the construction of a catalog of isolated galaxy pairs from the Uppsala Galaxy Catalog (UGC), using accurate radial velocities. The UGC lists 12 921 galaxies to δ > −2◦30′ and is complete to an apparent diameter of 1′. The criteria used to define the isolated galaxy pairs are based on velocity, interdistance, reciprocity and isolation information. A peculiar investigation has allowed to gather very accurate radial velocities for pair members, from high quality HI and optical measurements (median uncertainty on velocity differences 10 kms⁻¹). Our final catalog contains 1005 galaxy pairs with ρ > 2.5, of which 509 have ρ > 5 (50% of the pairs, i.e. 8%of the UGC galaxies) and 273 are highly isolated with ρ > 10 (27% of the pairs, i.e. 4% of the UGC galaxies). Some global properties of the pair catalog are given.