Astrolabes are probably the the sini qua non of ancient instruments. They have been collected for centuries, and forgeries have been made for centuries, though genuine, working, astrolabes were made in Islamic countries up through the nineteenth century. For background information on astrolabes a number of books are available…The Astrolabe site on the Internet provides a brief essay on the astrolabe, museums having astrolabe collections, a history of the astrolabe, and finally, astrolabe links, references, and reproductions, including a “personal astrolabe” available for a fee made by that site’s creator. Thanks Chris! Link.