Patek Philippe presents the self-winding flyback chronograph Ref. 5976 in 18K white gold as the second anniversary model to commemorate the 40^th birthday of the Nautilus collection. It is a symbolic choice because its predecessor, the Ref. 5980 was the first Nautilus chronograph that in 2006 crowned the casually elegant Patek Philippe collection when it celebrated its 30^th birthday.

However, the current anniversary chronograph Ref. 5976 in 18K white gold comes in a limited edition of 1300 watches of a distinctly more prominent format. With a width of 49.25 mm (3 to 9 o’clock, including screw-down crown), it is 3.6 mm wider than the predecessor model. This format emphasizes its unique aesthetic appeal with the bilateral case bulges. Both chronograph pushers are harmoniously integrated in the design and conveniently operable. Moreover, the crisp legibility of the chronograph functions was further optimized.

From the case and bracelet to the foldover clasp, the watch highlights Nautilus-typical finissage techniques such as the vertically satin-finished bezel with shiny chamfers and the alternating matt/mirror-polished bracelet links, all meticulously executed by hand. These lavish finishes underscore the nobility of 18K white gold and bring the contrasting dark blue dial to the fore.

It benefits from the larger format of the watch and affords more space for the enlarged aperture date that is set in a mirror-polished white-gold frame. The monocounter at 6 o’clock has grown as well, which makes it easier to read the results of short-time measurements. Its three concentric scales include the 12-hour counter on the outside as well as the minute counters from 1 to 30 in the middle and from 31 to 60 on the inside.

The applied hour markers – flawless Top Wesselton baguette and princess-cut diamonds – discreetly encircle the dial and accentuate its finesse. It features the horizontal Nautilus-style embossed decor and, in the upper half of the dial, the anniversary citation "1976 – 40 – 2016".

The proprietary chronograph movement CH 28-520 C, developed and crafted in-house, is wound automatically by a heavy 21K gold central rotor. The start/stop and flyback/reset chronograph functions are controlled by a classic column-wheel mechanism with a vertical disk clutch that handles the engagement and disengagement operations.

Because it is virtually friction-free, the chronograph hand can be used as a continuously running seconds hand without causing mechanical wear. Further features include the instantaneous date change with a switching cycle of one-tenth of a second as well as the Gyromax® balance invented by Patek Philippe. The balance is paired with a patented Spiromax® balance spring made of high-tech Silinvar®. It is totally antimagnetic, corrosion-resistant, and breathes concentrically thanks to the Patek Philippe terminal curve in the hairspring plane, which further optimizes isochronism.

This highly precise micromechanical marvel with a rate tolerance of -3 to +2 seconds per day can be observed at work: the Ref. 5976/1G is endowed with a sapphire-crystal back that also reveals the elaborate finissage details: the gold rotor and bridges with Geneva circular graining, chamfered and polished edges, polished bores and gold-filled engravings accentuated with blued screws as well as sparkling ruby-red bearing jewels.

The Nautilus Chronograph Ref. 5976/1G 40^th Anniversary in 18K white gold is being crafted in a limited edition of 1300 numbered watches. Each one comes in an anniversary box that also contains the Certificate of Origin and an anniversary document. Made of brown natural cork, the box is an authentic replica of the stylish 1976 original.

Like the original Nautilus, it evokes vivid associations with the proud ocean liners that inspired the porthole design of the casually elegant timepiece. The 40^th Anniversary cork box features polished stainless steel frames for the base and the hinged cover. The steel plaque on the front side, also a faithful replica of the 1976 original, displays the collection name “Nautilus” in cursive script and the PATEK PHILIPPE GENEVA signature logo.

Limited edition	:	Anniversary model in a limited edition of 1300 watches
Movement	:	Caliber CH 28-520 C Self-winding mechanical movement with flyback chronograph, column wheel, vertical clutch, date
Overall diameter	:	30 mm
Height: Overall	:	6.63 mm
Basic caliber	:	5.2 mm
Calendar module	:	1.43 mm
Number of parts	:	327
Number of jewels	:	35
Power reserve	:	45 to 55 hours
Winding rotor	:	Central rotor in 21K gold, unidirectional winding
Balance	:	Gyromax®
Frequency	:	28,800 semi-oscillations per hour (4 Hz)
Balance spring	:	Spiromax®
Balance spring stud	:	Adjustable
Hallmarks	:	Patek Philippe Seal
Crown	:	2 crown positions: Crown pushed home: To wind the watch Crown pulled out: To set the time
Displays	:	With hands from the center: Hours Minutes Chronograph/seconds hand With hands on the monocounter dial at 6 o'clock 60 minutes (0-30, 31-60) 12 hours With aperture (at 3 o'clock): Date
Chronograph pushers	:	Start/stop at 2 o'clock Reset/flyback at 4 o'clock
Correction push piece	:	Date at 8 o'clock
Case	:	18K white gold Sapphire-crystal glass Sapphire-crystal back Screw-down crown
Water resistant	:	120 m (12 bar)
Dimensions
Diameter (10 to 4 o'clock)	:	44 mm
Width (9 to 3 o'clock incl. crown)	:	49.25 mm
Length (lug to lug)	:	49.60 mm
Height (crystal to display back)	:	12.16 mm
Dial	:	Base material brass Sunburst beneath blue PVD coating Horizontal Nautilus embossing Anniversary embossing "1976 – 40 – 2016" 12 applied hour markers: 18K white gold with baguette and princess-cut diamonds (total weight approx. 0.29 ct.) Baton-style hands for hours and minutes in 18K white gold with Superluminova coating Chronograph/seconds hand sandblasted rhodiumed steel, counterbalanced 60-minute and 12-hour chronograph counter hands, brass, white lacquered
Bracelet	:	Link bracelet in 18K white gold
Clasp	:	Foldover clasp in 18K white gold