In the course of a systematic search in the “Technical Museum” of Vienna for instruments of astronomical importance, a Moorish astrolabe with Cufic lettering was discovered by the present author. Being labelled as “sun-moon-dial” its correct function had not been recognized before or forgotten. The device came into the museum’s possession in April 1937 through exchange with a theodolite from the Jesuit College at Kalksburg where the astrolabe had been kept after it remained in Vienna during one of the two Turkish sieges of the city (probably in 1683). The brass instrument has a diameter of 15,7 cm and is well equipped with 8 ṣafīḥas ( = tympans). Its conservation state is rather good, even the original red and gold ‘ilāqa ( = cord) is in place. The specimen is of undated planispheric northern type (shamālī musattah). It shows the typical small kursī ( = throne) of occidental instruments, cast in one piece with the ḥajra (= limb) and umm ( = mater) forming the main body of the astrolabe. This fact sets it apart from instruments of European origin where the kursī sometimes was fastened with screws to the main body (W. Morley, reprinted in R. Gunther, 1976).