Therefore, I personally suggest using copper, and first set the direction of sitting outdoors. Don't use the comprehensive disk. You learn the stars flying in the sky, so it's better to use ternary disk, or Li Juming's eight-game disk, which is better to use. It's on Taobao, but you'd better have a look after buying it. If you have a professional compass, you'd better compare it. In addition, look at whether the scale of the outermost circle is accurate, and look at it with a protractor. ...
I hope it helps you.