How long until sunrise? Is there enough daylight left for a little bike ride this evening? Where in the sky is the moon? The newest astronomical function by Ludwig Oechslin answers all of these questions. With day/night strapped to your wrist, the following information is available to you with a quick glance:

  • Length of day and nighttime for the location of your choice. This adjusts dynamically!
  • Solar noon
  • Sunrise and sunset
  • The position of the sun and moon in the sky
  • The moon phase, date and time.

Personalize your location and design

Your day/night watch will have a custom-made part which syncs it to your chosen location. Should you decide to change your place of residence in the future, we can easily install a new part to adapt the location for you. ochs und junior watches are sold exclusively directly. Design your personal day/night using our customizer. It would be our pleasure to guide you through the design and purchase process for your personal watch.

Former cofounder introduction

In the video above, Beat Weinmann introduced Ludwig Oechslin’s astronomical watch. It is our pleasure to personally answer your questions about day/night (Contact).

Reading the functions

The video above shows an entire month in 3 minutes! A complete list of day/night’s functions can be found below.

Daytime and nighttime

The light and dark-colored areas around the dial show the length of day and night. The lines separating them represent the horizon. The horizon fans move up or down every 10 days to account for seasonal changes (demonstration video).

Sunrise and sunset

Sunrise is when the sun passes from the darker colored area of the dial into the lighter colored area. Sunset is when the sun passes from the lighter colored area to the darker colored area.

Moon phase

You can imagine the center of the watch as representing the earth. The moon’s position in relation to the sun indicates the moon phase. When the moon is beneath the sun, it is new moon, when the moon is opposite the sun, it is full moon.

Solar noon

Using the pusher at 6 o’clock, solar noon (when the sun is at its highest point in the sky) can be set for your location (demonstration video).


The date indication at 6 o’clock is used to set the watch. The reason this watch does not feature a date spiral is that the dial holds gear wheels near the perimeter, as can be seen in the image below.

Sun and moon position

When facing south, the position of the sun and the moon on the dial indicates the direction in which you will find these heavenly bodies in the sky (demonstration video).


The following parts were designed by Ludwig Oechslin specifically for day/night. They are manufactured in Switzerland by Helfenstein Mechanik AG and, like all ochs und junior parts, are backed by a lifetime warranty.

  1. Hour wheel on hour pinion with friction
  2. Transition wheel 1 for moon and sun cogwheels
  3. Transition wheel 2 for moon and sun cogwheels
  4. Sun cogwheel
  5. Moon cogwheel
  6. Date disc
  7. Gear wheel between date disc and annual wheel
  8. Year wheel with crank pin in the size of the deflection of the horizon fans
  9. Carriage with cogs to move the horizon fans
  10. Horizon fan
  11. Horizon fan
  12. Module board
  13. Dial

The base movement for day/night is the Ulysse Nardin UN-320.

Further information


40mm x 11mm (incl. crystal); also available in 43mm upon request.


61g in titanium (incl. leather strap and buckle)
90g in sterling silver 925 (incl. leather strap and buckle)

Water resistance

100m in titanium, 100m in sterling silver 925. Both models are fit for almost any situation in daily life.


2-part case designed by Ludwig Oechslin. Available in grade 5 titanium or sterling silver 925; additional materials upon request. Visible machining marks. ochs und junior watches require no movement ring due to the extremely small manufacturing tolerances on the case. Available exclusively with a solid case back. Manufacturer: Helfenstein Mechanik AG / Alpnach / Switzerland.

Base movement

Ulysse Nardin UN-320 with a power reserve of 48 hours. Manufacturer: Ulysse Nardin SA / Le Locle / Switzerland.


Screw-down crown designed by Ludwig Oechslin in grade 5 titanium or sterling silver 925. Manufacturers: Pibor SA / Glovelier / Switzerland and Helfenstein Mechanik AG / Alpnach / Switzerland.


Designed by Ludwig Oechslin for 22mm watch straps with no loops. Visible machining marks. Grade 5 titanium or sterling silver 925, additional materials upon request. Manufacturer: Helfenstein Mechanik AG / Alpnach / Switzerland.

Watch straps

We offer over 80 possibilities, which you can explore in our straps pages: sturgeon, leather, suede, rubber.

Sapphire crystal

The sapphire crystals are manufactured by Stettler in Lyss / Switzerland. Both sides are treated with anti-reflective coating by Econorm in St-Imier / Switzerland.

Reading the time in the dark

To assure optimal readability of the time in the dark, we use Super-LumiNova X1. This coating is manufactured by RC TRITEC in Teufen / Switzerland. In principle, all Pantone colors can be made. Super-LumiNova is always applied in conjunction with a color pigment. The brighter the color, the better the luminosity. In the dark, Super-LumiNova shines green (the option used by ochs und junior) or blue, on special request. The Super-LumiNova coating is applied by hand by ochs und junior, or for dials with a color application by Cador in Eimeldingen / Germany and by Monyco in La Chaux-de-Fonds / Switzerland.

Swiss made

The ochs und junior day/night watch is manufactured entirely in Switzerland. The base movement Ulysse Nardin UN-320 is produced in Le Locle / Switzerland. Each watch is hand-assembled and regulated at the ochs und junior workshop in La Chaux-de-Fonds.

Lifetime warranty

A lifetime warranty covers all parts invented by Ludwig Oechslin, and the entire watch is covered by a 2-year guarantee. ochs und junior’s small scale and direct sales model allow it to offer uniquely fast and competent service.


Ludwig Oechslin’s rigorously simple designs, the fact that we individually manufacture our parts, and the direct relationship we have with our clients enable us to offer the highest possible degree of customization. The customizer shows many possibilities.