Abstract
Observations of Venus made during 1967 and 1968 at a frequency of 15.4 gigahertz set an upper limits of 5 percent for the variation of brightness temperature with phase. This negative result appears to contradict earlier detections of a phase effect. By comparison with Virg A (3C 274), which has an assumed flux density of 29 x 10-26 watt per square meter per hertz, the brightness temperature of Venus at this frequency is 485 + 60, -40°K (mean error).