News · Yema

Yema puts sidereal time and a flying tourbillon in the Spacegraf

A rotating star map and the CMM.32 calibre share a 42 mm titanium case in a 150-piece edition.

Hen & Mills Editorial · 4 min read · 14 October 2026

• Yema’s 150-piece Spacegraf Heure Sidérale has a star-map disc that turns once every sidereal day, 23 hours, 56 minutes and four seconds.
• The Grade 5 titanium case is 42 mm wide, contains the CMM.32 flying tourbillon and is rated to 100 metres.
• Yema lists US$16,000, €14,500, £13,100 and CHF 12,090 regionally, with December 2026 shipping; Australia is priced in US dollars.

Yema's Spacegraf Heure Sidérale places two kinds of motion on one dial. A star-map disc at twelve turns at the rate of a sidereal day, while a flying tourbillon turns below the hands at six. The result is the brand's most elaborate Millésime watch of 2026, limited to 150 numbered pieces. The important detail is that the celestial display is driven at a different rate from the ordinary time display. This is more than a constellation printed on a static dial.

What the celestial disc actually does

The disc makes one revolution in 23 hours, 56 minutes and four seconds, the period Yema gives for the Earth's rotation relative to the stars. That is just under four minutes shorter than the civil day shown by the hour and minute hands. Its purpose is to keep the star map moving with sidereal time, rather than simply using the sky as decoration. Yema connects the idea to the Besançon Observatory, established in 1878 to help local watchmakers set their instruments by astronomical observation.

The small display sits under a sapphire cover that fades from smoky to clear. The deep-black dial around it has a sandblasted grain and black PVD coating, with circular-brushed minute and seconds tracks. Yema applies blue-glowing Super-LumiNova BGW9 Grade X1 to the celestial disc as well as the numerals, tracks and hands. The luminous treatment makes the upper display part of the watch's night-time reading, although the size of the map means it should be understood as a compact indication, not an observatory chart.

A tourbillon occupies the other half

At six o'clock the open aperture exposes the flying tourbillon of Yema's CMM.32 calibre. A flying tourbillon has no upper bridge across the visible cage, so the mechanism can be seen more freely from the dial side. That visual openness balances the enclosed star disc above it. It also gives the face a clear vertical order: slow celestial rotation, conventional hands in the middle, then the much faster regulator below.

The CMM.32 stores 105 hours of power in one large barrel, according to Yema. The brand describes non-magnetic components designed to tolerate fields up to 2,000 gauss. That is a maker specification, not the result of an independent test of this watch. The sapphire caseback shows deep-blue movement bridges engraved with constellations and a flame-blued ratchet wheel carrying an Earth motif. The thematic work continues through the movement rather than stopping at the dial.

Yema says the bridges and mainplates are made in its Morteau workshops, with other movement components and exterior parts produced across a regional French and Swiss supply network. The product page's origin table identifies movement design as Swiss and assembly as French. That is a more useful description of the manufacturing claim than treating the entire calibre as if every component came from one room.

Titanium for a complicated dial

The Grade 5 titanium case measures 42 mm across and 12.15 mm thick, with brushed flanks and lugs and a mixed-finish bezel. A double-domed sapphire crystal rises over the dial, while the display back is also sapphire. The watch is rated to 100 metres and has a push-pull crown. These specifications give the Spacegraf more everyday practicality than its open tourbillon aperture might suggest, though a water-resistance rating is no substitute for checking the crown before immersion.

The black leather strap narrows from 21 mm at the lugs to 16 mm at its Grade 5 titanium pin buckle. Its stitched, restrained finish keeps the face as the centre of attention. A metal bracelet would have made an already technical watch harder to read visually; the supplied leather makes the two apertures and bright hands do the work. As always with a thick domed crystal, the 12.15 mm case figure will not tell the whole story of how the watch sits under a cuff.

Spacegraf price and availability

Yema lists reference 60.26.32.06.TEL.L6 at US$16,000 on its US store. Its regional storefronts also display €14,500 for France, £13,100 for Britain and CHF 12,090 for Switzerland. The Australian country selection remains priced in US dollars at US$16,000; no separate Australian-dollar list price is shown. The product page says shipping is due in December 2026 and advertises an offer for Yema Privilege Platinum members. The edition is limited to 150 numbered watches.

The Spacegraf's strongest idea is its separation of ordinary and sidereal time. The tourbillon is the dramatic moving part, but the star disc is what gives this watch a reason to exist within Yema's line: it makes the difference between a solar day and a stellar one visible on the wrist. The buyer has to value that particular astronomical idea, not merely the presence of another tourbillon.