Shellflow. I. The convergence of the velocity field at 6000 kilometers persecond

We present the first results from the Shellflow program, an all-sky Tully-F isher (TF) peculiar-velocity survey of 276 Sb-Sc galaxies with redshifts be tween 4500 and 7000 km s(-1). Shellflow was designed to minimize systematic errors between observing runs and between telescopes, thereby removing the possibility of a spurious bulk flow caused by data inhomogeneity. A fit to the data yields a bulk-flow amplitude of V-bulk = 70(-70)(+100) km s(-1) ( 1 sigma error) with respect to the cosmic microwave background, i.e., consi stent with being at rest. At the 95% confidence level, the flow amplitude i s <300 km s(-1). Our results are insensitive to which Galactic extinction m aps we use, and to the parameterization of the TF relation. The larger bulk motion found in analyses of the Mark III peculiar-velocity catalog are thu s likely to be due to nonuniformities between the subsamples making up Mark III. The absence of bulk flow is consistent with the study of Giovanelli a nd collaborators and flow-field predictions from the observed distribution of IRAS galaxies.