Abell 2199 and Abell 2634 revisited

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Abstract
Previous Dn — σ work found surprisingly large negative peculiar velocities for Abell 2199 and Abell 2634. In order to assess these results independently we have made new spectroscopic and photometric observations. We report 141 new redshift, velocity dispersion (σ) and Mg2 index measurements, and photometry for 79 early-type galaxies. Special attention has been paid to linking the new σ measurements on to a standard system that minimizes systematic errors. While the Abell 2199 σ measurements are in good agreement with our previously reported FLEX values, for Abell 2634 galaxies the new σs are systematically lower. The FLEX measurements for some Abell 2634 galaxies appear to have been erroneous due to a smearing problem with the CCD detector. The new photometric data are in excellent agreement with previously reported values. We also present a new compilation of data for 72 early-type Coma cluster galaxies. Assuming that the Coma cluster lies at rest with respect to the cosmic microwave background frame, we derive peculiar velocities of −160±380 and −670±490 km s−1 for Abell 2199 and Abell 2634 respectively. We estimate that the likely systematic errors on these measurements are less than 200 km s−1. The derived peculiar velocities are considerably less than previous estimates and are not significantly different from zero.

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