Large-scale cosmic microwave background anisotropies in homogeneous, globally
anisotropic cosmologies are investigated. We perform a statistical analysis in
which the four-year data from the Cosmic Background Explorer satellite is
searched for the specific anisotropy patterns predicted by these models and
thereby set definitive upper limits on the amount of shear, (σ/H)0​ and
vorticity, (ω/H)0​, which are orders of magnitude stronger than previous
constraints. We comment on how these results might impact our understanding of
primordial global anisotropy.Comment: 12 pages (1 figure), uses RevTex and psfig, submitted to PR