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Five Equation of Time Watches

In honor of leap year – celebrated this year with an added day this month – we bring you five fantastic equation of time watches that track time even better than we do.

An equation of time watch shows the difference between true solar time (nature) and mean time (man’s time). True solar time varies from day to today because of the Earth’s orbit and its axis. Mean time ignores the variations of the days and divides the year mathematically into equal hours and equal days

Only four days are actually exactly twenty-four hours long: April 15th, June 14th, September 1st and December 24th. All other days are either longer or shorter. This difference, which varies from about less than 16 minutes and 23 seconds on November 4th to plus 14 minutes and 22 seconds on February 11th, is how we derive equation of time.

The equation of time watch enables the wearer to view true solar time (in addition to mean time) on the watch dial. Most of these complex watches also display the equation of time – the difference in hours and minutes between mean and solar time – via a running equation wherein two different hands indicate mean and solar time. Others display an arc or subdial with +/- signs and numbers, and the wearer needs to do a little math to calculate true time from mean time.

Often, these watches have other sophisticated complications built into them, including astronomical displays and moonphase.

Here are five impressive equation-of-time watches.

Blancpain Villeret Equation of Time

From Blancpain, this Villeret Equation of Time watch is crafted in either a limited edition of 88 pieces in platinum ($192,700), or a limited edition of 188 pieces in rose gold ($171,300). The watch is powered by the self-winding Caliber 3863 movement with 397 parts. In addition to the running equation of time, the watch offers perpetual calendar, retrograde moon phase, small second hand a white grand feu enameled dial.

Audemars Piguet Royal Oak Equation of Time

This Audemars Piguet Royal Oak Equation of Time ($69,200) with blue central hand enables a precise reading of the daily variation, while the sunrise and sunset times – on smaller dials and selected to display a location chosen by the owner – are displayed on the 3 and 9 o’clock counters. The watch is powered by the Caliber 2120/2802 Manufacture-made movement offers 40 hours of power reserve. In addition to equation of time and sunrise, sunset times, the Audemars Piguet Royal Oak Equation of Time offers perpetual calendar, astronomical moon and hours/minutes. Interestingly enough, the complication is housed in a stainless steel case with silver-toned dial with Grande Tapisserie pattern.

Patek Philippe Ref. 6102R-001

This Patek Philippe Ref. 6102R-001 rose gold men’s complication watch ($283,500) includes indication of sidereal time. Sidereal time is based on the earth’s rotation in relation to a fixed point, such as a star. It is invariable for a given point and shorter than the average time of 3 min. 56 sec. per day (23 hours, 56 minutes, 4 seconds /24 hours). The watch is powered by a 315-part mechanical self-winding movement (Caliber 240LU Cl C) an offers celestial time with date, hours and minutes of mean solar time, sky chart, phases of the moon (and orbit), time of meridian passage of Sirius and of the moon. The 44mm rose gold watch features black sapphire-crystal disks for sky background and moon phases, a transparent sapphire-crystal disk for the sky chart and Milky Way and a sapphire case back.

Panerai Radiomir 1940 Equation of Time 8 Days

Luminor 1950 Equation of Time 8 Days

You may recall that Panerai last year debuted two equation of time watches, each with an unusual linear equation of time display that shows the difference between mean solar time and apparent solar time. The 200-piece limited edition Radiomir 1940 Equation of Time 8 Days (PAM00516; $25,400) and the 100-piece limited edition Luminor 1950 Equation of Time 8 Days (PAM00601; $25,900) retain their uniquely Panerai design, despite the addition of such a sophisticated complication. Panerai actually released its first equation of time watch at SIHH 2010, the 50mm PAM365. These two newer models feature more moderately sized cases: One of the watches has the 48mm Radiomir 1940 case and the other the 47mm Luminor 1950 case.

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