W&W 2020: Vacheron Constantin Les Cabinotiers Astronomical striking grand complication – Ode to Music

The collection „La Musique du Temps” includes a series of exceptional chiming watches. The new Les Cabinotiers Grande Complication Astronomique à Sonnerie Ode to Music is based first and foremost on a minute repeater which determined the construction of the entire calibre. 

The starting point was the Manufacture 1731 movement, due to its extreme slimness for a minute repeater mechanism. At just 3.90 mm thick, the 1731 calibre offers a 60-hour power reserve and a very good sound quality, in particular due to the development of an entirely silent flying strike governor. 

This movement has therefore been reworked to accommodate the astronomical complications. With the new 1731 M820 calibre, this timepiece is thus equipped with 19 complications housed in a 7.84 millimetres slim construction. One of the great challenges was to index the running equation of time to the minute repeater while maintaining an extreme slim construction.

The repeaters soundtrack has been recorded by the Abbey Road Studios

Perpetual calendar and solar time

The date is indicated by a serpentine hand in a snailed counter at 3 o’clock for an improved legibility. The days, months and leap years are discreetly displayed in windows between 12 and 2 o’clock. The date is indicated by the moon phases and age, but also the day / night indication which is coaxial to the moon phases. The lower part of the dial shows the pointer-type display of sunrise and sunset times, complemented by a linear indication of the length of day and night. A 4 o’clock aperture also reveals a disc bearing the signs of the zodiac, seasons, solstices and equinoxes.

Les Cabinotiers Grande Complication Astronomique à Sonnerie Ode to Music

This timepiece is first and foremost an astronomical watch which, in addition to the civil time indicated by the two central hands, also displays the particularities of solar time. This time difference is known as the equation of time, or time correction in astronomical parlance. For this timepiece, the company’s master watchmakers have chosen the more complex solution to display the equation of time. This consists in also displaying solar time by means of a central minutes hand, in this instance symbolically serrated, and thus enables instantaneous reading of both civil and solar time. 

The indication of sidereal time is on the back of the watch

Sidereal time

The indication of sidereal time can be viewed on the back of this timepiece, with a sky chart formed by two superimposed sapphire discs. Taking a fixed star in the sky as a reference point, the time it takes the Earth to complete a full 360° revolution, or sidereal day, is exactly 23 hours, 56 minutes and 4 seconds. Since the Earth both spins on its axis and revolves around the sun, it takes about four minutes less than a calendar day to return to its point of departure in relation to the given star. On this model, the first lower mobile disc is rimmed by a sidereal time scale punctuated by the cardinal points, which thus rotates in step with sidereal time. 

Still on the same disc, an off-centred blue ellipse serves as a transparent indicator of the constellations of the celestial vault, which are positioned on the fixed upper disc. This mechanism thus reveals the vision of the sky in motion as seen from a given point on Earth. This same second disc also bears a white ellipse for the celestial equator and a red ellipse for the ecliptic. While the first is a projection of the equator onto the celestial sphere that considers the Earth’s approximately 24° inclination, the second represents – from a heliocentric point of view – the plane of the Earth’s orbit serving as a reference for celestial coordinates. Finally, one notes an intense blue dial bearing the months of the year. 

The difference between the sidereal day and the mean or average day means that the movable lower disc will accelerate daily by some four minutes in relation to the fixed outer disc, so as to indicate the current month at exactly midnight by means of a yellow arrow. 

Housed in a pink gold case measuring 45 mm in diameter and barely 12.54 mm thick, the calibre accommodates the sky chart corrector and the minute repeater slide on the case middle. This calibre is also able to offer simultaneously a minutes repeater and the civil, solar and sidereal time.

The Les Cabinotiers Grande Complication Astronomique à Sonnerie Ode to Music is worn on a midnight blue alligator leather strap with pin buckle. Price on request. 

www.vacheron-constantin.com

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