Groups of Galaxies in the Las Campanas Redshift Survey

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A "friends-of-friends" percolation algorithm has been used to extract a catalogue of drho/rho = 80 density enhancements (groups) from the six slices of the Las Campanas Redshift Survey (LCRS). The full catalogue contains 1495 groups and includes 35% of the LCRS galaxy sample. A statistical sample of 394 groups has been derived by culling groups from the full sample which either are too close to a slice edge, have a crossing time greater than a Hubble time, have a corrected velocity dispersion of zero or less, or contain a 55 arcsec "orphan" (a galaxy with a "faked" redshift excluded from the original LCRS redshift catalogue due to its proximity --- i.e., within 55 arcsec --- of another galaxy). Median properties derived from the statistical sample include: line-of-sight velocity dispersion sigmaₗos = 164 km/s, crossing time tcr = 0.10/H₀, harmonic radius Rₕ = 0.58/h Mpc, pairwise separation Rₚ = 0.64/h Mpc, virial mass Mᵥir = (1.90x10¹3)/h Mₛun, total group R-band luminosity Lₜot = (1.40x10¹1)/h² Lₛun, and R-band mass-to-light ratio M/L = 153h Mₛun/Lₛun.