Loose groups of galaxies in the las campanas redshift survey

A "friends-of-friends" percolation algorithm has been used to extract a catalog of δn/n = 80 density enhancements (groups) from the six slices of the Las Campanas Redshift Survey (LCRS). The full catalog contains 1495 groups and includes 35% of the LCRS galaxy sample. A clean sample of 394 groups has been derived by culling groups from the full sample that 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 contain a 55″ "orphan" (a galaxy with a mock redshift that was excluded from the original LCRS redshift catalog due to its proximity to another galaxy - i.e., within 55″). Median properties derived from the clean sample include a line-of-sight velocity dispersion σ_los = 164 km s^-1, crossing time t_cr = 0.10 H^-1₀, harmonic radius R_h = 0.58 h^-1 Mpc, pairwise separation R_p = 0.64 h^-1 Mpc, virial mass M_vir = 1.90 × 10¹³ h^-1 M_⊙, total group R-band luminosity L_tot = 1.30 × 10¹¹ h^-2L_⊙, and R-band mass-to-light ratio M/L = 171 h M_⊙/L_⊙; the median number of observed members in a group is three.