Digital setting circles – What are they?
[Geoff Gaherty] Digital setting circles consist of two parts: encoders on the two axes of the telescope, and a small hand control containing a computer. You tell the computer the date and time, and it suggests a couple of stars to orient itself. You point the telescope at the two stars one after the other, and the computer will then give you instructions to point at any object in its database. Usually it does this with a couple of readouts. You move the telescope until both readouts are zero, and the scope should then be pointing at the selected object. A GoTo telescope works exactly the same way, except that the pointing is done by motors, rather than by the operator manually moving the scope. The main advantages of digital setting circles over GoTo is that they are less expensive, consume far less battery power, and are silent in operation.
