Astrolabe: obverse

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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 d ay 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.Michael D. Piquer Show more