Astrolabe with a single tympanum for latitude 43°40' (Florence). It is placed on an octagonal table, whose inclination is adjustable. There are a rete and an alidade. The planisphere is surrounded by: the calendar with the names of the months; a shadow square engraved on an arc in an eccentric position; a zodiac circle; a Tychonic scale for dividing the degrees into twelve parts; a windrose; and a degree scale.
The instrument was preserved in the Uffizi Gallery, and Galileo himself used it for astronomical calculations. For this reason it is known as "Galileo's astrolabe."