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Atomic Timekeeping / Super Titanium™
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When breakthrough technology and spectacular design meet, the Tsuki-yomi A-T is reading the moon. It’s the world’s first moonphase watch combined with atomic timekeeping innovation from Citizen, and this 30th Anniversary model is nothing short of impressive. The styling embodies the moon’s surface and a window at 6 o’clock displays the current moon phase. The timepiece measures 43mm in a silver-tone Super Titanium™ case, where sharp faceted edges pair with an elevated design throughout for an eye-catching aesthetic on the wrist. The blue dial works in tandem with black accents and silver-tone touches for a display that’s as handsome as it is legible. In addition to its running time, the watch features a moon phase display, world time in 24 time zones, a perpetual calendar, and day-date functionality. Powered by Citizen’s proprietary Eco-Drive technology to provide light-powered vitality without ever needing a battery. Water resistant up to 100 meters. Caliber H874.

Tsuki-yomi A-T
Orders with sizing require additional processing time.
Bracelet sizing adds additional processing time.
- Bracelet sizing requires an extra 1-2 business days for processing, prior to shipping, as sizing is handled on demand by one of our expert technicians.
- Orders placed after 2pm on Friday or on weekends will ship from our facility on Monday (excluding holidays).
- Overnight shipping is available for an additional fee.
Free Bracelet Sizing
5 Year limited warranty
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Monday, Tuesday, Wednesday: 10AM to 7PM
Thursday, Friday, Saturday: 10AM to 8PM
Sunday: 11AM to 7PM


Product Details
Model
- BY1010-57L
- 12/19/2023
Movement Technology
- H874
- Eco-Drive
- Powered by any light source, continuously and sustainably, eliminating the need to replace watch batteries.
Case Width (mm)
- 43
Lug Width (mm)
- 22
Band Type
- Bracelet
- Super Titanium
Case Material
- Silver-Tone
- Super Titanium
Crystal
- Sapphire Crystal
- Superior scratch resistance and hardness
Clasp
- Fold Over Clasp with Push Buttons
Dial
- Blue
Water-Resistance
- WR100/10Bar/333ft [Swimming, Showering & Snorkeling]
Additional Functions
- Moonphase
- World Time in 24 Time Zones
- Radio Control
- Perpetual Calendar
- Day-Date
- Atomic Timekeeping
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Reviews

I can’t say enough god things about this particular watch. It looks great, the watch arrived on time and very well packaged. The atomic clock sync works great, I live in NC and it works, just wait for the nightly sync if it doesn’t work during daytime hours. Love the functionality, moon phase looks great and works great, all the features Citizen chose to implement are useful and make this watch a must have for every day.

This watch purchase was to replace a 20 year old Tag Link Chronograph, for +- every day use. While I enjoyed the nuances of the prior automatic watch, and the look of the Chronograph (the functions of which I rarely used....), I was always having to check to see if it was precise on time or needed winding after a day or two of rest. I looked at Tag, Omega and Breitling Quartz versions, for a change of pace from the automatic. All were 2-3k, with very limited choice of Quartz > Automatic. It felt like each brand viewed their Quartz versions as "lesser than." I researched the Citizen choices and purchased this watch on the website, not having seen it in person. I was intrigued by the use of titanium and the Eco Drive Radio Controlled device. The watch has radio controlled time regulation from six atomic clocks. I was curious what it would be like to have a watch that always had the precise time and correct date... I also liked the look of the moon phase. The background is just enough of a difference, without being too much. The watch is beautiful and well made. It goes nicely with casual clothes or a full suit in a business setting. I have had numerous compliments. The only difference is the weight. As advertised, the titanium is more durable but lighter. When I first put it on, I was worried it might feel too light, just in terms of comparison to prior stainless steel bands. But after five days of wearing, I can attest it is actually much more comfortable. Its reserve is not 45 hours, or 90 hours. It is 6 months. From my perspective, the look of this watch is equal or better to the other competitors I mentioned. It keeps perfect time. If you must have a watch with a different name, I get it. But I must say, I am really enjoying doing something copletely different.

There are several things I love about this watch: - It’s beautiful - It synchronizes automatically with the atomic clock - The date window and day of the week dial are readable. (In many watches, the date window is microscopic and impossible to read without a magnifying glass) - The moon phase indicator is cool, and you don’t have to be an astronomy geek to appreciate it.

Saw this on email from you guys! Beautiful watch! Ordering was easy and straightforward. Price was reasonable. Delivery was quick and it arrive in perfect condition. Thank you Citizen.

Where do I start? The watch is absolutely beautiful. I'm a huge space nerd and own a dobsonian telescope. I love stargazing and everything sci-fi. The moon phase is such a cool feature. And the moon backdrop is stunning. Combined with radio syncing with an atomic clock, you have perfect time. I should add, I live in Riverside County California and the watch receives the nightly signal just fine, even in a box. The Super Titanium gives the watch a feather weight feel. Last with Eco-drive, it will run for years. This watch is eco-friendly, will run forever, is super tough, and has unrivaled precision. It is almost a Perfect Blend of technology and timekeeping. My only complaint is the dead-beat seconds. Seriously, that's it. I pray Citizen doesn't solve the Eco-drive/deadbeat seconds because my bank account would be devastated.

Having had a Citizen watch with more functions than I could use, and after several years, it finally needed some serious repairs, so off it went. My wrist felt naked without the thick, old watch, so I went shopping for a new Citizen. I wanted one that told the day and date, but was spot-on accurate. I found it in this super titanium model has a lithium battery that is kept recharged by any light that strikes the face. It is kept accurate daily with the WWV radio time signal, and internal workings change the 12 hour and 60 seconds hands, day/date, day of week, follows AM/PM, can be switched to southern or northern hemisphere, and tracks the phases of the moon, with a moving disk, in the manner of my grandfather clock. With the case being made of super titanium, the watch and link band weighs only 3.5 oz. and it rides only 3/8" above my wrist, and doesn't snag on my choir cassock like the older watch always did. And, although I take it off when I shower, it is water resistant to 10 atmospheres (333 ft.)

Very pleased with the whole purchase process. My watch was delivered within days of ordering and it was sized properly and day, date, time and moon phase were all set. I’m a happy customer!

This is by far my favorite watch. The things it can do that it fit in just one watch and the self setting option, the accuracy the moon phase. I have never seen something so good at such an attainable price and it’s a crime they are not talking about this more. My only complaint is that I wish there was a women’s design version of this. I’m a female and I want an elegant sporty atomic watch with moon phase.
This is if i had to guess, somewhere between 7 or 10th Citizen time piece. And thus far my favorite. Don't tell the other pieces. Lol.
I bought this watch because I fell in love with the blue dial, story, and technology that this watch represents. I own a Navi Hawk that I've had for 25 years that never failed and now I've added the moon to my wrist! The one suggestion I would give is to remove "Titanium" and "radio controlled" from the dial and replace it with Tsuki-yogi, the name of the watch and 30th, to celebrate the anniversary of the moon technology. Other than that this is a dream timepiece. 👍🏽🙏🏽
A very classy watch, great for an active lifestyle, and a great elegant look for a night out. Highly recommend it!!
Bought this to replace my Calendrier and I wish I had found this first. Half the weight but twice the watch. Atomic moon phase is epic. The Calendrier moon phase I had was always off but not anymore. And for the price I genuinely can’t think of a better way watch.
Best watch in my Citizen collection of atomics. Been wanting this one for a while and it does not disappoint. The dial contrast makes it easy to read at a glance. The watch is insanely light, almost forget it’s on your wrist. Bought is for the 1st ever atomic moon-phase and the beauty of the design.
Best watch in my Citizen collection of atomics. Been wanting this one for a while and it does not disappoint. The dial contrast makes it easy to read at a glance. The watch is insanely light, almost forget it’s on your wrist. Bought is for the 1st ever atomic moon-phase and the beauty of the design.
Perfect everyday watch
This watch isn't only beautiful but it's a great size. It's light weight which makes it a great everyday watch.
Great watch
I can’t say enough god things about this particular watch. It looks great, the watch arrived on time and very well packaged. The atomic clock sync works great, I live in NC and it works, just wait for the nightly sync if it doesn’t work during daytime hours. Love the functionality, moon phase looks great and works great, all the features Citizen chose to implement are useful and make this watch a must have for every day.
Citizen Response Thank you for your review! We’re happy to hear you love your new watch, especially the atomic clock sync and moon phase features. The Tsuki-yomi A-T was designed with both style and function in mind, and we appreciate your positive feedback and support. We hope you enjoy your timepiece for years to come!
Tsuki-yomi A-T
Excellent experience leading to an excellent purchase. Citizen Watch customer service was awesome in answering my questions and providing watch options based on my 'wants'. The watch was easy to set up and looks great!
Great watch
I love this watch and planning to buy the red/purple one. Extremely pleased with the purchase.
Tsuki-yomi A-T
Watch (with the blue face) is stunning and functions perfectly. It arrived running and all I had to do was adjust to my time zone. Ordering and delivery process was outstanding - from order placement to delivery was 4 days including bracelet adjustment by Citizen. This is my first Citizen and will not be my last!
Beautiful and Practical
After tiring of having to adjust Automatics each morning I decided to take another look at Citizen's eco-drive. I routinely wear long sleeved shirts and my previous eco-drive could not stay charged. My new Tsuki=yomi AT watch has an impressive power reserve allowing it to continue to keep excellent time under the cuff before again getting decent light. The dial is large enough that my old eyes can see what I want but not as 'busy' as dive watches which now allows me to tell the time from a quick glance. The moon phase feature is not something I need but it is kind of cool. The Atomic Time keeping works well in my location without special handling of the watch. All in all I am VERY HAPPY with this watch
Amazing Watch Experience!
This is exactly what I was hoping for when I purchase it if not more. the attention to details, the amazing technology, the weight and the looks of this watch gives you a select feel of premium and confort. Amazing watch in every sense.
Beautiful watch
I purchased the 30th anniversary moon phase watch for my husbands Christmas gift. He owns several but his favorite stopped working so I wanted to replace it with a newer watch. He’s very happy. It’s a beautiful watch and, as always, very well made.
My second favorite Citizen.
Other than my Octavia, this is my favorite Citizen watch. There isn’t anything I dislike and I love that it sets the time and date everyday without my help.
Love this watch
This is my new favorite watch!