Collection: Atomic Timekeeping Watches

Atomic timekeeping watches, explained

An atomic timekeeping watch sets itself. Each night it listens for a radio time signal broadcast from an atomic clock and corrects its time and date, so it stays on the exact time without you touching the crown. Every watch on this page is a Citizen, most of them marked A-T for atomic timekeeping, and every one runs on Eco-Drive, so it charges from light and never needs a battery.

Where the signal comes from

Citizen’s A-T watches can pick up five signal stations in four regions: WWVB at Fort Collins, Colorado; DCF77 at Mainflingen, near Frankfurt; BPC in Henan, China; and two JJY stations in Japan. In North America the watch listens for WWVB, which Citizen’s manuals show with a reception radius of about 3,000 km. Reception happens on its own overnight; the Skyhawk A-T, for example, tries at 2, 3 and 4 a.m. If the watch can’t pick up a signal, it keeps going as an ordinary quartz watch, accurate to within about 15 seconds a month, until the next good night.

Getting a good signal

Worn during the day and left by a window at night, most of these watches simply take care of themselves. If one isn’t updating:

• Take it off and set it down near a window, on a surface where it won’t move. If the glass has wire mesh in it, open the window or try another spot.
• Keep it away from cars, reinforced concrete, electrical appliances and office equipment, and phones in use.
• Make sure it’s charged. If the second hand is jumping every two seconds, the charge is low and the watch won’t try to receive; give it daylight first. Our guide to how Eco-Drive works explains charging.
• You can start a reception by hand at any time. Leave the watch still; on the World Chronograph A-T it can take up to 15 minutes.

Which A-T watch

• Promaster Skyhawk A-T (45 to 46 mm, calibre U680): the pilot’s model, with time for 43 cities, UTC, a second time zone, two alarms, a countdown timer and a chronograph to a hundredth of a second.
• Perpetual Chrono A-T and Promaster Sky (42 to 46 mm, calibre E660): analog, with a chronograph, world time and a perpetual calendar. The Perpetual Chrono A-T CB5898-59E is the 42 mm steel version on a bracelet.
• World Chronograph A-T (43 mm, calibre H800): under 12 mm thick, with 26 time zones and a chronograph to a twentieth of a second. Citizen counts the blue AT8020-54L among its Blue Angels editions.
• Promaster Geo Trekker (46 mm, calibre H864): 26 time zones, a world-time disc and resistance to magnetism.
• Tsuki-yomi A-T (43 mm Super Titanium, calibre H874): adds a moon phase to atomic time and world time in 24 zones.

Questions

Is this the same as Satellite Wave GPS? No. Citizen’s Satellite Wave GPS models take the time from GPS navigation satellites. The watches on this page use radio signals from the ground stations above, received overnight.

What happens when I travel? Set the watch to the city or time zone you’re in. Inside one of the four regions it picks up the local station; elsewhere it keeps quartz time until you’re back in range.