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Omega DDR Observatory Chronometer

CHF 5,000


Extremely rare and well-preserved finest precision 18K Yellow Gold 52mm Lépine OMEGA / Louis Brandt & Frère, S.A. Observatory Competition chronometer Ref. 743.20, Cal. 20”’ LO Grade DDR pocket watch, made in 1905. Only 396 pieces of size 20”’ DDR (LO – Lépine) were crafted in 1905 and 1908. This particular movement SN: 2362051 was chosen for observatory competitions and submitted for trials in 1911, 1912 and 1913 to the Observatory of Neuchâtel, where achieved quite a good results, thanks to Omega precision timer “regleur” Werner A. Dubois.

Marco Richon explained this movement type in his book “Omega: A Journey Through Time”: “The exceptional precision and the supreme workmanship of this chronometer embody the highest quality ever achieved by a manufactory at the turn of the century…” The “DDR” code stands for the highest level of quality OMEGA produces.

Competition chronometer-quality movements are not “ordinary” C.O.S.C. certified movements. These movements were designed and finished to excel in the rigorous world of Observatory Competitions, as conducted in Geneve and Neuchatel. Precision movements are made to much smaller mechanical tolerances than standard watch movements and often take as long to manufacture and regulate as complicated movements. Precision watches were also prized possessions and were often reserved for the manufacturer’s best clients.

The original certificates “Bulletin de Marche” are no longer available from the observatories – but A. Hidding copied a lot of their records, so you can order a copy of the bulletin from his website. Based on information provided in these records this chronometer was used for 3! competitions in 1911, 1912 and 1913 in the Observatory of Neuchâtel.

Case: Three-body, “lépine”, solid, polished, hinged gold cuvette. Dial: White enamel with bold Paris numerals, outer black minute track, sunk subsidiary seconds dial. Blued steel “spade” hands. Movement: Silvered nickel Cal. 20”’ LO Grade DDR, 23 jewels, 18 in gold chatons, Guillaume balance with gold and platinum timing screws, 2 diamond endstones, blued steel Breguet balance spring, excentric cam regulator, gold wheel train. Diam. 52 mm. Dial, movement and case signed.

Up until 1967, the exact length of a second was determined by the Earth’s motion around the sun, and the Neuchatel observatory’s precise optics allowed the fine measurements necessary for precise timesetting to be made. Because of this, Neuchatel began to host observatory chronometer trials – a series of the most stringent, thorough accuracy tests in the history of mechanical watchmaking. The trials, held over a period of forty-five days, encompassed ten separate movement timekeeping tests in five different positions and two temperatures. These observatory trials quickly outgrew their roots as a simple certification test, and before long the trials at Neuchatel were a competitive battleground for the finest watchmakers in Europe. Names like Longines, Zenith, Peseux, Omega and many more traded records for decades, fighting to produce the most accurate movement possible. These movements were never intended for regular use, and bore little to no resemblance to what these companies offered their consumers. Along with the technical prowess of the watchmakers building the movements, in the “racing team” there were specialists, the “regleurs de precision”, who worked tweaking a number of movements until they could find a few of them to bring to the Observatory Competitions. By means of fine adjustments, replacement of key parts, use of special lubricants, they could create a few movements for the Competitions. And often they were the same movements for many years.

Watch is in overall great condition, running and ready to use!


Brand Omega
Model Observatory Competition Chronometer, DDR Grade
Reference Ref. 743.20
Year 1905
Movement Hand-winding
Calibre Cal. 20”’ LO Grade DDR
Case material 18K Yellow Gold
Case size 52 mm
Features observatory competition chronometer
Box/Papers no box, no papers


In fully working order. Very good condition 8/10, minor surface scratches, scuffs and discolorations through the age. Minor damage on the crown. Practically invisible hairline on the dial near 8 o’clock position. See photos.

Watches are sold as-is, and there is no guarantee of to be waterproof or movement accuracy, due to the nature of vintage watches. Please view all the pictures carefully as they form an integral part of the description. Any defects not mentioned but visible in the pictures will be considered as described.


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