This astrolabe presently comprises two tympanums, for latitudes 30° and 40°, the other for latitudes 36° and 42° (corresponding to the regions between Persia and the Black Sea). There is an alidade, a rule, and a rete. The back carries a double shadow square and the zodiacal calendar.

The instrument comes with a tooled black leather case (cover missing) containing a sixteenth-century manuscript note stating that the astrolabe was brought from Spain and dates from 1252. The astronomical data inscribed on the astrolabe suggest it may have been built before 1000. According to tradition, the instrument dates from the period of Charlemagne (9th C.). A very similar Arab astrolabe is documented in a drawing by Antonio da Sangallo il Giovane [the Younger] (c. 1520?) at the Gabinetto dei Disegni e delle Stampe (Department of Drawings and Prints) of the Uffizi. Provenance: Medici collections.