On about page 15 of Harry Potter and the Philosophers' Stone, Dumbledore (headmaster of Hogwarts, School for Witchcraft and Wizardry) takes out his pocket-watch. It has no numbers, but instead, little planets moving round the edge: very much the same idea as an Almagest (a lot more portable, though).
Our researchers report that an even more similar instrument is described in Book Four (page 499). This is a miniature model of the solar system, housed in a glass dome, brought out from under a chair by Professor Trelawney.
So if you're an aspiring wizard, get yourself an Almagest (or persuade someone else to get one for you!).