MERLIN observations of superluminal radio sources

Powerful extragalactic radio sources may all be members of a single family in which those showing superluminal behaviour are the ones in which a relativistic jet is directed towards the observer. The superluminal sources are shown to have extended radio structures the form of which is consistent with such a unified scheme. This interpretation requires that the Hubble constant H0 should be nearer to 100 than to 50 km s−1 Mpc−1.