It’s being hailed as one of the most complicated watches ever made by the International Watch Company of Schaffhausen.  Best know for its high precision instrument watches and pilot’s watches, IWC has taken the connection with the world of the sky and stars hinted at by the navigation instrument inspired watches in its collection and brought it to an unprecedented new level.  The Portuguese Sidérale Scafusia gets its name from a different way of telling time: sidereal time, or “star” time, used by astronomers to calculate the position of stars in the sky.  An ordinary watch tells mean solar time –that is, it’s based on the time it takes for the sun to return to a particular point in the sky.  That period is defined as 24 hours.  A star, however, takes slightly less time to do the same thing –that’s because the Sun is much closer, and the Earth’s movement along its orbital path is added to its rotation, which means the Earth actually has to turn slightly more than one revolution for the Sun to return to a given point in the sky.  A sidereal day is slightly shorter than a solar day (23 hours, 56 minutes, and 4.1 seconds.)  The sidereal time indication is accurate to within  11.5 seconds per year.

The sidereal time dial shares space on the front of the watch with a power reserve indication, as well as the standard time display, but there’s also one of the most unusual tourbillons ever made, visible through an aperture in the dial.  The tourbillon has been fitted with a special constant force mechanism –basically a second, miniature mainspring that is wound by the primary mainspring once per second.  The idea is to make sure that the tourbillon always receives a constant amount of power (ordinarily as a watch runs, the mainspring unwinds and the force going to the regulating mechanism gets steadily weaker.)  This combination of constant force mechanism with the tourbillon makes the Sidérale Scafusia one of the rarest watches ever made –in the entire history of watchmaking only a handful of watches have had this combination.

The visual and intellectual feast continues when you turn the watch over –on the back is a star chart that shows the night sky over the owner’s home city, as well as the time of sunrise and sunset.  Since this display has to be customized for each owner’s chosen location, each watch is unique.  There’s also a calendar display that shows the number of each day of the year (February 10, for instance, is shown as the number 41.)  If it’s a leap year, the calendar automatically adds an extra day to the year.

This extraordinary watch offers a combination of extremely rare complications and great visual beauty, but it’s as much a treat for the head as for the heart.  It’s a superb example of technical know how and sheer beauty, and the few who are lucky enough to own one can rest assured of having something that’s their own private piece of Heaven.

The IWC Sidérale Scafusia is customized with a star chart and sunrise/sunset indication specific to the owner’s home city of choice.  In addition each watch will be further personalized with a range of options for dial, strap, and case material offering over 200 different options, and IWC is pleased to accept any additional requests for customization.  As each watch is created individually, the IWC Sidérale Scafusia is available only by special order from IWC.  At introduction the announced price for the IWC Sidérale Scafusia is CHF 750,000.

Jack Forster is the Editor in Chief of Revolution Magazine, a quarterly publication celebrating the world of fine watchmaking, and he also manages Revolution Online the foremost information and discussion site on the internet for watch enthusiasts.

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