On the determination of heliographic positions and rotation velocities of sunspots

The north-south asymmetry in the intensity of the 530.3 nm emission coronal line is examined in the time period 1958 to 1980 using data at all latitudes. The results show that overall the northern hemisphere of the Sun is more active in this line. The general pattern has changed after the beginning of the 21st cycle with the southern polar region being more active after the last solar minimum (1975). These anisotropies may be related to phase differences between the activity of northern and southern hemispheres. North-south asymmetries may have implications in the structure and evolution of the heliosphere, its current sheet and even in the cosmic ray propagation.