Results of radar observations of Venus at the 39 cm wavelength in 1980

Over the period from February 15 to April 15, 1980 radar observations of Venus were carried out with a new fully steerable parabolic antenna in the range of 161-94 million km. Distances from the planet, its motion velocities, surface altitude profiles in the longitude range of 70 deg-230 deg were measured. The deviation of the measured distance from the predicted one, calculated on the basis of new numerical theory of planet motion, did not exceed 6 km for root mean square values of measurement errors of 0.3-1.5 km. Two mountain areas devided by an extensive hilly plain were observed in the investigated Venus region. One of them reached the height of 4.5 km, whereas the other reached 2.5 km at the longitude of 195 deg. These areas lengthed about 4000 km and 2500 km correspondingly