A “ friends-of-friends ” percolation algorithm has been used to extract a catalogue of \delta n / n = 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 clean 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 contain a 55-arcsec “ orphan ” ( a galaxy with a mock redshift which was excluded from the original LCRS redshift catalogue due to its proximity to another galaxy — i.e. , within 55 arcsec ) .
Median properties derived from the clean sample include : line-of-sight velocity dispersion \sigma _ { los } = 164 km s ^ { -1 } , crossing time t _ { cr } = 0.10 ~ { } H _ { 0 } ^ { -1 } , harmonic radius R _ { h } = 0.58 ~ { } h ^ { -1 } Mpc , pairwise separation R _ { p } = 0.64 ~ { } h ^ { -1 } Mpc , virial mass M _ { vir } = 1.90 ~ { } \times~ { } 10 ^ { 13 } ~ { } h ^ { -1 } ~ { } M _ { \sun } , total group R -band luminosity L _ { tot } = 1.30 ~ { } \times~ { } 10 ^ { 11 } ~ { } h ^ { -2 } ~ { } L _ { \sun } , and R -band mass-to-light ratio M / L = 171 ~ { } h~ { } M _ { \sun } / L _ { \sun } ; the median number of observed members in a group is 3 .