On the apparent position of a source at a large Doppler factor

In cases exhibiting superluminal separation, the observed transverse expansion of the moving components should indicate that the ejection takes place with a significant angular extent. At a large Doppler factor, such an ejection would result in a shift of its apparent source position toward the line of sight. In the case of a bent beam, the overall apparent motion would be an expansion rather than a separation. Thus very small viewing angle is an unlikely source of superluminal motion