Compact galaxy groups in 3D

3D Observations in the context of compact galaxy groups involve Fabry-Perot, HI and CO observations that provide full 2D velocity mapping. These data can be very important for both inferring the 3D distribution of galaxies in a group as well as the temporal history of the group. These observations have provided some of the strongest statistical evidence that compact groups are dense interacting systems. They have also been indispensable for detailed study of relatively nearby groups that serve as useful analogs to interaction processes thought to be much more common at high redshift.