Improved upper limits of gravitational deflection of polarised radiation

Some further interferometer measurements are reported of the total bending of microwave radiation by the sun's gravitational field. A search was made for any polarisation splitting based on an analysis of data obtained with the four-element interferometer at the National Radio Astronomy Observatory, New York, for three small diameter radio sources - 0116 + 08, 0119 + 11, and 0111 + 02. Improved upper limits were obtained for differential deflection and reasons are given for this improvement. No polarisation splitting was observed, but upper limits were calculated for polarisation splitting. (U.K.)