Experience unmatched precision with the Citizen Tsuki-Yomi, powered by Eco-Drive technology that never needs a battery. This radio-controlled moon phase watch calculates lunar phases from signals, offering ±15 seconds accuracy per month.
Introducing the Citizen 'Tsuki-yomi' Radio-Controlled Moon Phase - the world's first light-powered radio-controlled moon phase movement. To celebrate the 30th anniversary of the first CITIZEN radio-controlled watch they are debuting the world's first fully analogue moon phase function for light-powered watches.
The Tsuki-yomi collection (directly translating to reading the moon) features a new radio-controlled Eco-Drive Cal. H874 movement that provides ±15 seconds accuracy per month, revolutionary proprietary Super Titanium material and artfully crafted moon pattern dials. Based on a unique mathematical formula developed by CITIZEN called Luna Program, the watch calculates the phase of the moon each day from signals received from multi-band radio transmitters. The phase of the moon at the six o'clock position is then automatically adjusted and displayed. With a striking pattern of the moon's surface on the dial paired with a black outer ring, and a date display at the 4 o'clock position.
Sustainably powered by any light, including moonlight, with our proprietary Eco-Drive technology, this timepiece never needs a battery.
| Guarantee | 5 year guarantee included |
| Movement | Eco-Drive |
| Country of origin | Japan |
| Shape | Round |
| Water resistant | 100m |
| Watch type | Classic |
| Strap material | Metal |
| Batteries included | Yes |
| NFC enabled | No |
| Brand | Citizen |
| Manufacturer's warranty | 5 years |
| Bracelet type | Bracelet |
| Composition | Titanium |
| Model name / number | BY1010-57H |
| Finish | Polished |
| Strap colour | Silver |
| Watch face colour | Silver |
