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Andreas Strehler - Lune Exacte

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Andreas Strehler is a Swiss independent watchmaker which started his career in the workshops of Renaud & Papi. In 1995 he set up his own business as an independent watchmaker and watch repairer becoming, in 2001, the youngest watchmaker to be admitted as a member of the Horological Academy of Independent Creators (AHCI) at just 30. While remaining independent, he also worked as Technical Director of the company H. Moser & Cie winning the Grand Prix d’Horlogerie de Genève in the Complicated Watch category, with the Moser Perpetual 1, in 2006.

His Sauterelle à Lune Perpetuelle model set a Guinnes World Record as the watch with the most precise moon phase indication. In fact, while most moon phase indications deviate from the synodic or mean moon by one day after a couple of hundred years, Andreas Strehler's phase of the moon would require an adjustment only after two million years!

However, despite achieving the highest accuracy, a problem - common to all moon phase indications - remained: except at new moon and at full moon, the wearer of the watch had to guess the exact phase or age of the moon. Indications could not be read very precisely. Also, the exact setting of the moon phase indication was only possible at new moon or full moon.

With the new Lune Exacte, Andreas Strehler approaches this problem with the first high-precision phase of the moon indication, giving the age of the moon in days and further increments of three hours.


Thanks to its new and patent pending mechanism, the Lune Exacte can be read and set correct to three hours at any time and not only every fortnight.

On the openworked dial of the watch, there is a conventional phase of the moon indication as well as an additional display, based on a Vernier scale, at 6 o'clock.


The red arrow indicates the age of the moon in days. Two red marks on the scale indicate new moon and full moon. A Vernier scale on the inner ring increases the accuracy of the indication to three hours.

The pictures below help to understand how the moon Vernier scale indication works.


The red arrow indicates the age of the moon in days. If the arrow points to a number in the yellow sector of the outer scale, the hours value can be read from the yellow sector of the inner Vernier ring. The age of the moon accurate to three hours is indicated where the next mark on the Vernier ring aligns with a mark on the outer ring. In the first picture on the left, it indicates 18 hours that must be added to the days. The resulting age of the moon is 5 days and 18 hours.

In the same way, if the red arrow indicates a day on the blue sector of the outer scale, the hours
can be read from the blue sector on the Vernier scale. In the last picture on the right, the age of the moon is 27 days and 3 hours.

The Lune Exacte also features Andreas Strehler's patented remontoir d'égalité, first presented in the Sauterelle (we wrote about it here).


Instead of adopting a force constant complication which is mounted on the escapement wheel, Strehler placed a remontoir d'egalité on the seconds wheel to guarantee a constant and linear supply of energy to the balance.

Every second the visible satellite gear provides exactly the same amount of energy to the seconds
wheel while displaying the seconds as dead-beat seconds.

The satellite wheel (charged by the mainspring) which acts on the seconds wheel supplying constant energy once every second

This solution has the advantage that the complete escapement, including the escapement wheel, moves freely between two impulses, uninfluenced by the movement. This way, Andreas Strehler reduced to the minimum outside factors that may impact precision like fluctuations in the supply of energy, flaws in the gear train, variations in  temperature and viscosity of lubricants.

Moreover, in contrast to a constant force mechanism and its fixed division ratio, which demands a frequency of 18,000 vibrations per hour, the remontoir d'égalité can be used at any frequency. In fact, the beautifully finished movement of the Lune Exacte beats at 21,600 vibrations per hour so delivering higher precision.


The typical case has a size of 41.00 mm x 37.30 mm and is available in red gold or in platinum.

The Andreas Strehler Lune Exacte has a price of Swiss Francs 112,000 in red gold or Swiss Francs 125,000 in platinum. astrehler.ch

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