Piquer was a monk in the monastery of the Holy Cross in Catalonia. His astrolabe bears no date, but in the past has always been dated to around 1585 because the vernal point (the day on which the apparent path of the sun crosses the path of the Earth's equator), situated on the ecliptic on the rete, coincides with a point just after 20th March, thus incorporating the effect of the Gregorian calendar reform of 1582. However, Piquer's other two astrolabes are dated 1542, thus creating an unlikely gap of 40 years. A close look at the ecliptic inside the rete of the NMM astrolabe reveals that the original calendar has been burnished out (probably some time after 1582) and replaced with the new, reformed version. Close inspection reveals traces of the original engraving. Thus the astrolabe can be dated much earlier to around the 1550s. It has a specially shaped red leather case that may well be original.

The simple yet elegant throne is cast in one piece with the limb. There are two plates with all four sides showing stereographic projections for latitudes 33º-36º/39º-42º and 45º-48º/51º-54º. The rete, comprising 41 flames-shaped pointers, is finely cut into a pattern that resembles leaf motifs and on its reverse is the signature: 'D Michaël Piguer coenobij sanctarum crucum in cathalonia monachus faceibat Louanij'. There is a universal orthographic projection on the back of the instrument. On the rule is an inscription from the 'Astronomica', an unfinished astrological poem by the Roman poet, Marcus Manilius (1st century AD). The selection of such a passage possibly indicates that the intended owner was a humanist scholar, as the circulation of Manilius's text was almost exclusively limited to this select group.