Since VLBI techniques give microarcsecond position accuracy of celestial objects , tests of GR using radio sources as probes of a gravitational field have been made .
We present the results from two recent tests using the VLBA : In 2005 , the measurement of the classical solar deflection ; and in 2002 , the measurement of the retarded gravitational deflection associated with Jupiter .
The deflection experiment measured \gamma to an accuracy of 3 \times 10 ^ { -4 } ; the Jupiter experiment measured the retarded term to 20 % accuracy .
The controversy over the interpretation of the retarded term is summarized .