If you use the stacking technique you can get full circles within a year if you stack your images from different seasons… No matter which direction. But if you want to acheive a true Star trail circle in one night you will need to point south for us in OZ. Also you would need to do a 3 to 4 hour exposure, your battery would be empty before your camera could take a shot. Unless you have one big Battery or a Generator.
So my trick is to take a a few photo’s and stack them together, this one shot took nearly 12 months.
Same deal l used for this shot, the exception was l used the moon;