Speedmaster Professional Moonwatch 3861 Stainless Steel - Sedna Gold / Pink

In Context

At 42 mm it is sized to the current mainstream: 40 mm is the median across every watch measured in this catalogue. At 13.18 mm it is a tall case, and it will catch on a cuff. The case back is open, so the movement is visible without taking the watch apart, and the sapphire crystal will resist everything short of deliberate abuse. 50 m covers rain and hand-washing comfortably; it is not a watch to swim in.

The movement is hand-wound, so winding it becomes part of the day rather than something the watch does for you. 50 hours of reserve is enough to set it down on Friday evening and find it still running on Monday. At 21,600 vph the seconds hand advances 6 times a second, the slower and more audible rate of an older design.

310.20.42.50.99.001 stands on its own in this catalogue — no other reference here shares its base number. It pairs a pink sunburst dial with a sedna gold, stainless steel case. Beyond the time it carries a chronograph.

The 3861 is the Moonwatch movement since 2019. It is the hand-wound chronograph of the Speedmaster Professional rebuilt with a co-axial escapement, a silicon hairspring and Master Chronometer certification. It powers 35 watches in this library. It keeps the layout and the cam-actuated chronograph of the [1861](/calibers/omega-1861), which had run the Moonwatch since 1997 on the architecture of the 1969 861, and changes what is inside: the [co-axial escapement](/glossary/co-axial-escapement), the Si14 silicon balance spring, a free-sprung balance, and a hacking seconds, which the Moonwatch never had before. The reserve rises to 50 hours at 21,600 vph, with 26 jewels at 27 mm across, and the movement passes the METAS tests, including 15,000 gauss, that the [Master Chronometer piece](/blog/master-chronometer-what-metas-tests) describes. It debuted in the Apollo 11 anniversary editions of 2019 and became the standard Moonwatch movement in 2021. In the library it powers 32 [Speedmaster Moonwatch](/brands/omega/speedmaster) references, in steel with hesalite or sapphire crystals and in gold, and 3 [First Omega in Space](/brands/omega/speedmaster-first-omega-in-space) references at 39.7 mm. The [1861](/calibers/omega-1861) is the movement it replaced, the [1863](/calibers/omega-1863) the decorated version of that movement, and the [9906](/calibers/omega-9906) the hand-wound Master Chronometer chronograph of the Speedmaster '57.

34 other watches in the library run the Omega 3861.

Omega

Speedmaster Professional Moonwatch 3861 Moonshine Gold / Green

310.63.42.50.10.001 · 42 mm

Omega

Speedmaster Professional Moonwatch 3861 Canopus Gold - Rainbow / Silver - Rainbow / Bracelet

310.55.42.50.52.002 · 42 mm

Omega

Speedmaster Professional Moonwatch 3861 Stainless Steel / White / Sapphire

310.32.42.50.04.002 · 42 mm

Omega

Speedmaster Professional Moonwatch 3861 Moonshine Gold / Moonshine Gold

310.62.42.50.99.001 · 42 mm