百達翡麗，精細及罕有，18k金自動上弦天文腕錶，配星空圖表，月相及月亮軌跡，天狼星及月亮中天，型號5102J，附證書及盒子，約2009年製

Launched in 2002, the ‘Celestial’ is one of the most important horological complications ever developed. This astronomical wristwatch borrows the principle of the celestial canopy from the most complicated wristwatch ever produced by Patek Philippe - reference 5002, the Sky Moon Tourbillon. The nocturnal sky of the northern hemisphere rotates to show the apparent angular motion of the stars and moon as well as the progression of the phases of the moon. Hours and minutes are displayed by two pierced white hands. A delicate elliptical contour on the inside of the glass frames the portion of the sky visible from all cities sharing the latitude of Geneva. To determine the highest possible accurateness for the astronomical displays, the engineers of Patek Philippe researched 25 trillion (25,000,000,000,000) ratio combinations, showing the enormous horological challenge the model represents.

The highly sophisticated automatic movement calibre 240 LU CL consists of 301 individual parts, meticulously hand-finished in the workshops of Patek Philippe. Three sapphire crystal discs are used to simulate the orbit of the moon and the passage of the stars, hence rendering it a remarkable sense of depth. For the mechanical module for the astronomical displays the firm was granted Swiss Patent CH 688 171 B5.

Reference 5102 was launched in 2002 in white gold only. In 2007 it was replaced by the yellow gold version of which a total of approximately 200 examples was made. It was substituted in 2009 by the pink gold and platinum variant. Production ceased in 2012 when it was replaced by reference 6102. According to our research, the present lot is fresh to the market.