Swiss Astro Navigational deck watch with black 24 hour dial Circa 1959

Bronze and gilded keyless open faced deck watch by Ulysse Nardin
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A rare, large, and unusual Swiss bronze and gilded Astro Navigational keyless open faced deck watch with a black 24 hour dial simultaneously indicating the local time and an hour angle corresponding to the sidereal time, circa 1959. Invented by Oscar E. Batori and Raymond Nardin, it was made for Batori Computer Company Inc. New York.
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The watch features a damascened nickel movement with 30 jewels, two trains, complex gearing for solar and sidereal time, a planetary differential mechanism, fine precision adjustment, and a visible train. It is regulated by a lever escapement with a compensation balance made of a nonmagnetic and nonoxidizing alloy. Movement engraved SunStar Chronometer, Ulysse Nardin, Swiss, Batori and marked Pat. Pend. by R.N. and O.E.B., 11.8.58, Swiss Pat. 23.9.57. The black dial includes a luminous Arabic 24 hour display, central luminescent hour and minute hands, a subsidiary seconds dial at the base, and an hour angle corresponding to sidereal time in arc degrees. The minutes and seconds are indicated by the right and left subsidiary dials, along with the central red seconds hand. The right subsidiary dial is calibrated for 360 arc degrees, while the left subsidiary dial is calibrated from 0 to 10. The red central seconds hand indicates the angle in arc seconds on a scale of 0–60.
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The brass case features a gilded bezel, bow, pendant, and crowns, along with a gilded screw-down case back. The crown by 19 is turned in tandem with the olivette at 17 for adjusting the degree calibrated subsidiary dials, and there are nibs beneath 14 marked on off for starting and stopping movement. The glazed inner cuvette has a centrally mounted crown for adjusting the centre red hand, while the olivette above 22/23 is for adjusting the hour/minute hands via the crown. The inside back is signed and numbered Ulysse Nardin 715565.
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Diameter: 70 mm
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Signed: Ulysse Nardin
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This deck watch was commissioned by Oscar E. Batori of The Batori Computer Company Inc., New York. Three years before the watch’s production, Batori had visited Ulysse Nardin in Le Locle, complaining that Swiss manufacturers were refusing to supply him with prototype deck chronometers designed specifically for air navigation. Ulysse Nardin accepted the challenge to produce a watch that would indicate civil and solar time on a 24 hour dial with additional hands to indicate the Greenwich hour angle based on sidereal time, degree minutes, and arc seconds. All hands were to be connected by direct gears and have one regulated escapement system. To accommodate the complications, the watchmakers at Ulysse Nardin had to calculate two different gear trains connected with a differential. In addition, a system similar to a hack feature was developed to block the balance wheel so that the time could be set to the exact second. In 1960, Ulysse Nardin was awarded Swiss Patent No. 345.604 for their ‘Sun Star’ Deck Chronometer, and the following year, 1961, received U.S. Patent No. 2.969.636. In the U.K., a ‘Sun Star’ chronometer was tested on the ground and in the air and passed the Royal Observatory’s accuracy tests at Greenwich. As technology was rapidly developing in the early 1960s, the ‘SunStar’ deck watch’s system quickly became outdated, and consequently, very few examples were produced.
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The Batori Computer Company Inc. specialises in producing slide rules and other specialised navigational calculating equipment for pilots’ use.