MEASUREMENT OF THE SOLAR GRAVITATIONAL DEFLECTION OF RADIO-WAVES USING VERY-LONG-BASE-LINE INTERFEROMETRY

We made very-long-baseline-interferometry observations of the extragal actic radio sources 3C273B and 3C279 to measure the gravitational defl ection of radio waves by the Sun. Cross-correlation of data recorded a t antennas in California and Massachusetts at 2, 8, and 23 GHz during a ten-day period surrounding the October 1987 solar occultation of 3C2 79 yielded plasma-corrected group delays, from which we obtained gamma = 0.9996 +/- 0.0017 (estimated standard error), corresponding to a gr avitational deflection 0.9998 +/- 0.0008 times that predicted by gener al relativity.