Unlike on most astrolabes, the mater of this instrument, attributed to Hans Dorn, does not have a raised limb; in other words, it lacks housings for interchangeable tympanums on the front. The planispheric plate is fixed, and built for latitude 48° (Munich). On the plate rotate the rete and the rule, engraved with the northern and southern latitudes and the date 1483. On the back are the alidade with folding sights, the zodiacal calendar, the degree scale, and a housing for a small tympanum inscribed on both sides with the divisions of the days and months, a zodiacal division, and a zodiacal planisphere. Provenance: Medici collections.