We report a catalog of 509 pairs identified among 10403 nearby galaxies with line-of-sight velocities V _ { LG } < 3500 km/s .
We selected binary systems in accordance with two criteria ( “ bounding ” and “ temporal ” ) , which require the physical pair of galaxies to have negative total energy and its components to be located inside the zero-velocity surface .
We assume that individual galaxy masses are proportional to their total K -band luminosities , M = L _ { K } \times 6 M _ { \odot } / L _ { \odot } .
The catalog gives the magnitudes and morphological types of galaxies and also the projected ( orbital ) masses and pair isolation indices .
The component line-of-sight velocity differences and projected distances of the binary systems considered have power-law distributions with the median values of 35 km/s and 123Â kpc , respectively .
The median mass-to- K -band luminosity ratio is equal to 11 M _ { \odot } / L _ { \odot } , and its uncertainty is mostly due to the errors of measured velocities .
Our sample of binary systems has a typical density contrast of \delta \rho / \rho _ { c } \sim 500 and a median crossing time of about 3.5Â Gyr .
We point out the substantial fraction of binary systems consisting of late-type dwarf galaxies , where the luminosities of both components are lower than that of the Small Magellanic Cloud .
The median projected distance for 41 such pairs is only 30Â kpc , and the median difference of their line-of-sight velocities is equal to 14 km/s which is smaller than the typical error for radial-velocity ( 30 km/s ) .
This specific population of gas-rich dwarf binary galaxies such as I Zw 18 may be at the stage immediately before merging of its components .
Such objects , which are usually lost in flux-limited ( and not distance-limited ) samples deserve a thorough study in the HI radio line with high spatial and velocity resolution .