This astrolabe dates back to 1555 and was constructed by Michael Piquer, in Louvain. The base plate is unique in that it is engraved with two different latitudes. Divided in halves, this plate shows latitudes ranging from 33 to 36 degrees on the left and 39 to 42 degrees on the right.
This astrolabe can be used to determine the time of day in reference to the position of a specific star in the sky. In order to measure the time, the user will hold the instrument by the ring and look through the holes on the alidade to align the rule with the star. The alignment of the rule on the inner scale of the mater indicates the altitude of the star in degrees. The user then locates the specific star on the rete. The stars are indicated on the rete with flame-shaped pointers, which are labeled by name, planetary symbol and magnitude. The user must align the specific star pointer with the altitude circle that corresponds to the degree that was measured by the alidade. The alidade is then aligned with the present date found on the ecliptic. Finally, the date can be read on the outer scale of the mater, which is scaled by hour and divided into four minutes of time.
The back of this instrument is interesting as it consists of a universal orthographic project. This enables the user to find the time of sunrise and sunset from any location around the world.