3C 279 - The case for 'superluminal' expansion

The compact extragalactic radio source 3C 279 was observed with the Haystack-Goldstone interferometer (wavelength approximately 3.8 cm) during six separate sessions spread between October 1970 and April 1972. The fringe amplitudes from each of these observation sessions were consistent with a two-component model of the brightness distribution of the source. The position angle of the line joining the components remained at 38 + or - 2 deg, while the angular separation between the components increased nearly linearly at the rate of 0.5 + or 0.1 milliarcsec/yr during this period. The corresponding apparent expansion speed is (21 + or - 4)c, for H = 50 km/s per Mpc and q = 0.05