The moon phase display on the Portugieser Perpetual Calendar diverges by just 1 day in 577.5 years from the actual phase of the moon. In the model with the double moon display, the moon phase and its mirror image show the state of the moon in both the northern and southern hemispheres. The double moon model comes with the railway-track-style chapter ring typical of the Portugieser, while the designers have transformed the entire moon phase display into a star-studded night sky, so that the moon and stars appear to hover in infinite space. The elegant timepiece leaves virtually no wish unfulfilled: perpetual calendar, window showing the year in four digits, 7-day automatic movement with Pellaton winding and a power reserve display. This timepiece is powered by an IWC-manufactured movement from the 52000-calibre family, featuring a solid 5N gold rotor and blued screws. The 18-carat white gold watch has a blue dial and arched-edge front glass and comes with a black alligator leather strap.
CALIBRE FAMILY 52000
The highly efficient winding system is a refined version of the 50000-calibre family with a bidirectional Pellaton pawl-winding system. Two barrels provide an impressive 7 days’ power reserve. The winding pawls and the automatic wheel are made of black ceramic while the rotor bearing is made of white ceramic. These extremely hard high-tech materials make the automatic winding system practically wear-free. The indexless balance with a frequency of 4 hertz (28,800 beats per hour) and the Breguet spring guarantee maximum precision. The design and finish of the movement was also considerably enhanced. The proportions of the rotor and the inset “Probus Scafusia” gold medallion are noticeably slimmer.
In the early 1980s, IWC's head-watchmaker Kurt Klaus set out on an engineering journey to translate the Gregorian calendar with its many irregularities into a mechanical program for a wristwatch. His ingenious perpetual calendar, which debuted in the Da Vinci Perpetual Calendar in 1985, comprises only about 80 parts and displays the date, day, month, year in four digits, and the moon phase. The smart mechanical program automatically recognises the different length of the months, and even adds a leap day at the end of February every four years. The moon phase display is so precise that it will deviate from the actual phase of the moon by just one day after 577.5 years. All displays are perfectly synchronised and can be adjusted simply by turning the crown. Some models come with an additional century slide, so the watch can continue showing the date until 2499. The calendar only needs a small adjustment in those centurial years that skip the leap year, which is the case in 2100, 2200, and 2300. Some versions of the calendar feature a double moon phase display, showing the moon phase on the northern and southern hemispheres.
The double moon display shows the current moon phase for the northern and southern hemispheres simultaneously. In each lunar month, the moon’s orbit as displayed on the watch deviates by about 12 seconds. Thanks to its ingenious design, the double moon only needs to be adjusted by 1 day every 577 years.
SERIES: Portugieser Perpetual Calendar
DIAL: Blue dial
STRAP: Black alligator leather strap by Santoni Strap width 22 mm
WATER RESISTANT: 30 meters / 100 feet
CASE DIAMETER: 44.2 mm
HEIGHT: 14.9 mm
CALENDAR: Perpetual Calendar
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