We have obtained I-band photometry and velocity widths for galaxies in 24 clusters, ,spread out to about cz < 10,000 km/s.
We have investigated and derived methods for correcting for biases resulting resulting from sample incompleteness, catalog inaccuracies, cluster size, morphological type mix and other sources.
The sources of scatter in the TF diagram have been analyzed in detail. The error budget depends primarily on the rotational velocity variable and varies across the diagram.
We employ both HI line global HI widths and optical H-alpha rotation curves. The latter are especially important in clusters where galaxies are HI deficient, and at larger distances, where confusion within the radio beam becomes significant. We have constructed optical and radio TF analogs.
For her Ph.D. thesis, Nicole Vogt investigated the effect of environment on the TF relation.
For his Ph.D. thesis, Marco Scodeggio investigated the application of the Fundamental Plane relation and found consistency between the TF and FP distances for a set of clusters.
After applying the necessary corrections, an I-band TF template relation was constructed from cluster ensemble.
The peculiar velocities of the clusters were then estimated. Except for the nearby clusters (which move with us), the cluster ensemble is, within the errors, observed to be at rest with respect to the Cosmic Microwave Background.