Seiko 145th Anniversary Edition Astron GPS Solar-Powered Dual Time Zone Chronograph
Octagonal Titanium Case
To celebrate Seiko's 145th anniversary (founded by Kintaro Hattori in 1881), the brand has released four new Astron GPS solar-powered dual time zone chronographs. All four watches feature a 43.4mm hard-coated titanium case and are powered by the solar-powered 5X63 movement. The watches have a sporty appearance, further evidenced by their 100-meter water resistance. Of the four, my favorite is the limited edition HAB004, with its silver dial and blue and white silicone strap.
Seiko has released four Astron GPS solar-powered dual time zone chronographs: HAB001, HAB002, HAB003, and the limited edition HAB004. These watches were released to commemorate the 145th anniversary of Kintaro Hattori opening his first retail store in Tokyo in 1881. The modern Astron series takes its name from the 1969 quartz Astron watch, which replaced the traditional mechanical lever escapement with an integrated circuit and an 8,192 Hz quartz crystal oscillator. The current model uses the newly developed 5X63 movement, an upgrade to Seiko's GPS-synchronized solar-powered movement first introduced in 2012.
Its core technology lies in the miniature ceramic patch antenna ring located beneath the bezel. The high dielectric constant of ceramic allows for a significant reduction in the antenna's physical size while still resonating at the required GPS L1 frequency of 1575.42 MHz. To determine accurate local time, the receiver must receive signals from at least four GPS satellites orbiting the Earth. An internal processor calculates the precise spatial coordinates and corresponding time zone based on this triangulation. Satellites broadcast atomic clock data, which the movement decodes and corrects the hand position via an independent electromagnetic stepper motor. Even without a satellite network connection, the quartz oscillator maintains a reference accuracy of ±15 seconds per month within a temperature range of 5 to 35 degrees Celsius.
The GPS solar-powered watches launched in 2012 had relatively large cases due to the bulky antenna components and batteries in their early versions. By systematically reducing the size of the receiver module and improving the electrical efficiency of the motor, the 5X63 movement achieved a much thinner case structure. The commemorative HAB004 watch features a silver dial accented with specific blue elements, a color scheme historically linked to Seiko's technological developments in the mid-20th century.
Case and Dial
The case is precision-machined from titanium and treated with a special ultra-hard coating. Untreated titanium reacts violently with oxygen, immediately forming a titanium dioxide passivation layer upon exposure to air, giving it extremely high corrosion resistance and biocompatibility. Standard titanium has a lower Vickers hardness than 316L stainless steel, making it prone to surface wear. This ultra-hard coating is applied using physical vapor deposition in a vacuum chamber, firmly bonding a hardened carbon layer to the titanium substrate, increasing surface hardness and enabling it to resist daily wear while maintaining the metal's lightweight feel.
The case measures 43.4 mm in diameter and 12.4 mm in thickness, with a lug spacing of 50.0 mm. The 50.0 mm length ensures the case covers the flat surface of a standard wrist, while the downward-sloping lugs effectively reduce lateral protrusion. The bezel features a two-piece octagonal design. The top surface of the bezel employs a heavy linear brushing process, creating a matte finish, with parallel micro-brushing marks that scatter direct light. The bezel's edges are finely polished by a rotating polishing disc, resulting in a distortion-free, mirror-like shine; in low-light conditions, the beveled edges appear completely black. A sapphire crystal glass is fitted tightly to the inner edge of the bezel and coated with an ultra-clear anti-reflective coating, effectively preventing dial reflections and glare. A screw-down case back ensures the watch's 10 bar water resistance.
The dial design also functions as an optical filter. The dial surface is decorated with a dense pattern of intersecting triangular geometric shapes. This design cleverly conceals the amorphous silicon solar cells located beneath the dial. Amorphous silicon operates efficiently in both high-intensity ultraviolet light and low-light indoor environments. The dial's lacquer and substrate must allow sufficient photons to pass through to generate an electric current. The applied hour markers protrude above the dial surface, casting shadows that add visual depth. The central hour and minute hands, as well as the rectangular areas around the outer edges of each applied hour marker, are coated with luminescent material.
Three recessed subdials are symmetrically arranged along a horizontal axis. The subdial at 3 o'clock is a powerful multi-function indicator, displaying the day of the week, chronograph mode, standard time, daylight saving time, and alarm status. The subdial at 6 o'clock displays dual time zone hours and minutes on an internal 24-hour scale. The subdial at 9 o'clock is dedicated to displaying 1/20th of a second chronograph accuracy. A bezeled date window is located at 4:30; the date wheel color on the HAB002 grey and HAB003 black models matches the dial color.
The 5X63 movement utilizes photoelectric conversion technology. Photons penetrating the dial strike the solar panel, generating an electric current to charge the rechargeable lithium-ion battery. A full charge provides approximately six months of standard operation. An integrated energy-saving algorithm monitors the energy input. If the dial remains in darkness for an extended period, the integrated circuit stops sending electrical pulses to the stepper motor. The hands stop rotating to conserve current, while the internal logic board continues precise timing in the background for up to two years. When light returns, the motor quickly drives the gear train, aligning the hands with the currently calculated time. The 5X63's mechanical structure distributes each function to an independent stepper motor. Standard mechanical chronographs use a central wheel, friction clutch, and cams to drive the hands. The 5X63 eliminates this mechanical engagement. Pushers at the 2 and 4 o'clock positions act as electronic switches, sending signals to the integrated circuit to activate independent motors driving the central seconds hand and the sub-dial at 9 o'clock. During chronograph operation, the motor at 9 o'clock must rotate 20 times per second, consuming a significant amount of power reserve. Resetting the chronograph reverses the polarity of the electromagnetic pulses, instantly returning the hands to zero. The internal processor manages a perpetual calendar, pre-set with the precise length of each month, including leap years, so no manual date adjustment is needed until February 28, 2100. The world time function stores location data for 38 different time zones. The movement features a time-switching function, allowing the wearer to interchange the hometown time displayed on the central subdial with the local time displayed on the 6 o'clock subdial via a button.
The movement employs 14 jewels. Within the quartz frame, the synthetic jewels serve the same purpose as in mechanical movement: reducing friction and supporting the precision pivots of the stepper motor rotor and the simulated gear train. The internal electronics are shielded, providing antimagnetic performance up to 4800 A/m, protecting the motor from external magnetic fields generated by common electronic devices. A flight mode allows manual disabling of the GPS receiver to comply with aviation regulations regarding active radio frequency receivers.
Strap
The case structure integrates a proprietary quick-change system for the strap and bracelet. The traditional spring bar is replaced by a 14mm central connection point extending directly from the case. The bracelet links feature a double-pin locking mechanism at the end, controlled by an embedded button on the bottom. Pressing the button compresses the internal spring, retracting the side pin and releasing the link from the case structure. The titanium bracelets of models HAB001 and HAB002 use solid links coated with the same hardened layer as the case and secured with an easily adjustable triple-folding clasp. Models HAB003 and HAB004 are equipped with reinforced silicone straps. The silicone polymer has high tensile strength, maintains elasticity under extreme temperature gradients, and is more resistant to performance degradation caused by prolonged UV exposure than natural vulcanized rubber.
Technical Specifications
Case: 43.4 mm diameter x 12.4 mm thickness, 50.0 mm lug spacing, titanium with an ultra-hard coating, two-piece octagonal bezel, sapphire crystal with an ultra-clear coating, screw-down case back, water resistance to 10 bar, antimagnetic performance 4,800 A/m.
Movement: 5X63 GPS solar movement, ±15 seconds per month (without GPS signal), 14 jewels, 6-month power reserve, 2-year power saving reserve, perpetual calendar until February 28, 2100, world time (38 cities), dual time zone, time transfer function, automatic hand calibration.
Dial: Geometric interlocking triangle pattern, applied faceted hour markers, available in blue (HAB001), grey (HAB002), two-tone (HAB003), and silver dial with blue accents (HAB004). Hands and hour markers are coated with LumiBrite luminescent material. Recessed subdials are located at 3, 6, and 9 o'clock, and a date window is located at 4:30.
Strap: Titanium bracelet with an ultra-hard coating, featuring an easy-to-adjust triple-fold clasp (HAB001, HAB002); reinforced silicone strap (HAB003, HAB004); 14mm lug spacing; equipped with a dedicated quick-release system.
Reference numbers: HAB001, HAB002, HAB003, HAB004.