The Astron 5X Dual-Time.
The most advanced ever.

The world’s first GPS solar watch* takes things to the next level.

  • The world’s first GPS solar watch launched in September, 2012.


A completely new caliber with “high speed time zone adjustment” and a “time transfer function” capability.

To enhance the speed and quality of the GPS connection, every component in the GPS module has been re-engineered. Thanks to the use of three independent motors for the hour, minute and second hands, Caliber 5X requires at the fastest just three seconds* to change from one time zone to another.

  • Speed comparison of different movements: Tokyo→New
    York (14 hour time difference): 8X Series: 34 seconds, 5X Series: 3 seconds.

The “time transfer function” allows you to switch, simply and instantly,
the display of home and destination times between the main dial and the sub dial.

Just press simultaneously on the buttons at two and four o’clock and Caliber 5X  converts the main dial display from, for example, home time to local time with a single push. The sub-dial changes from local to home time at the same time.

Automatic synchronization to the exact time every day

Your Astron 5X watch adjusts automatically to the exact time every day.
If it can see the sky, it will connect with one or more GPS satellites and re-set the time, if needed, to a precision of one second every 100,000 years. Even if the watch cannot see
the sky, it remembers when it was last successful in receiving a time signal and automatically attempts to receive a signal.


Extremely compact size

The new Astron 5X series is the world’s slimmest*
GPS solar watch. The case is 42.9mm in diameter and 12.2mm in depth.

  • As of August 1, 2018. Based on Seiko’s research.

A new adjustment system for the buckle

A new buckle adjustment system allows you to make, at the touch of a button,
minor adjustments to the length of the bracelet that are so important when
temperature or other changes make the wrist expand or contract.