Considering its international launch at the European Southern Observatory at Paranal, Chile, the home of the project’s Very Large Telescope, it’s a pity IWC did not simply name its newest creation ‘Very Complicated Watch’...

...for that would have saved the non-specialist reviewer much time and trouble establishing the extraordinary lengths the Schaffhausen-based watchmaker has gone to in order to produce a watch that measures solar and sidereal time in two, separate displays.

‘Solar time’ is a reckoning of the passage of time based on the sun's position in the sky: 24 hours. ‘Sidereal time’, on the other hand, is a time-keeping system used by astronomers to track the direction of their telescopes in order to view a given star in the night sky. Subject to fiendishly complicated arithmetic it is, approximately, four minutes shorter than a solar, 24-hour day.

Just setting another pair of hands to run four minutes a day less than normal would be too easy – no, the craftsmen at IWC have come up with an ingenious movement, accurate to within 11.5 seconds in the course of a year, that incorporates a large tourbillon mounted at the 9 o’clock position. The hand-wound mechanism has a four-day power reserve.

All very impressive, for those among us adhering to the sidereal calendar, but the budding IWC Portuguese Sidérale Scafusia owner has another, highly complicated, trick (quite literally) up his sleeve. On the reverse of the watch lie three displays.

The first is a repeat of the solar and sidereal time display including sunrise and sunset. Then, an inner ring shows a 365-day calendar (including leap years). So far so good, but now the really clever stuff: the central section is devoted to a representation of the night sky and its constellations - as a celestial chart, with the horizon engraved in yellow - at the actual location of the watch-owner. Yes, as part of the 12-month production process, the engineers at IWC create a bespoke ‘location profile’ for each wearer.

Therefore, no two watches are likely to be the same (unless the location happens to be Monaco, perhaps) and the degree of personalisation can be further developed with different case materials, dial colours and variations in strap.

Despite its complexity, the IWC Portuguese Sidérale Scafusia is still waterproof to 3 bar and, for those planning on a little sub-aqua, handily incorporates a night/day indicator to remind an undersea wearer when it’s time to surface for cocktails.

For further information, see www.iwc.com.

Text: Steve Wakefield
Photos: IWC