Seiko’s 2026 Astron GPS Solar galaxy-dial limited editions share a dark turquoise glitter dial and an embossed spiral pattern, but they differ in size and complications. The SSJ039 is the smaller, simpler 3X62 model; the larger SSH187 adds a 12-hour chronograph, dual time and world time. Seiko lists each as limited to 1,500 pieces.
SSJ039 vs. SSH187 at a glance
| Specification | SSJ039J1 (SSJ039) | SSH187J1 (SSH187) |
|---|---|---|
| Edition | Astron GPS Solar 2026 Limited Edition; 1,500 pieces | Astron GPS Solar 2026 Limited Edition; 1,500 pieces |
| Caliber | 3X62 | 5X83 |
| Functions | GPS time-zone and time adjustment, date, perpetual calendar to February 28, 2100 | GPS time-zone and time adjustment, chronograph up to 12 hours in 1/20-second increments, dual time, world time for 38 cities, day display, perpetual calendar to February 28, 2100 |
| Case diameter | 41.2 mm | 43.3 mm |
| Thickness | 12.0 mm | 13.4 mm |
| Lug-to-lug | 48.6 mm | 49.5 mm |
| Case and bezel | Titanium with super-hard coating | Titanium with super-hard coating; ceramic/aluminum bezel |
| Crystal | Sapphire with super-clear coating | Dual-curved sapphire with super-clear coating |
| Water resistance | 10 bar | 10 bar |
| Approximate power reserve | About 6 months when fully charged; power-save mode about 2 years | About 6 months when fully charged; power-save mode about 2 years |
| Official US listed price | USD 2,400 | USD 2,900 |
Specifications and prices are from Seiko’s US product listings; the prices are listed US prices, not verified transaction prices, and can change. See Seiko’s SSJ039J1 page and SSH187J1 product information.
Which model is smaller?
The SSJ039 is smaller in every listed case measurement: its diameter is 41.2 mm versus 43.3 mm, its thickness is 12.0 mm versus 13.4 mm, and its lug-to-lug length is 48.6 mm versus 49.5 mm. Those dimensions make it the more compact choice on paper; they do not establish how either watch will fit or feel on a particular wrist.
What do the galaxy dials have in common?
Both models use a dark turquoise dial with glitter and an embossed spiral pattern. Seiko says the pattern radiates from the center to suggest flowing stars; “galaxy” describes the design inspiration, not astronomical imagery or scientific data. The shared dial concept is presented on both official product pages.
#1 Best Overall
![SEIKO Watch SBXY033 [ASTRON Solar Radio Line Metal Band Men] Shipped from Japan Relased in March 2022](https://m.media-amazon.com/images/I/41yXd-xgoUL._SL160_.jpg)
- Includes individual box, Japanese warranty (1 year), and individual box
- Solar radio wave correction function (receives standard radio waves in Japan, China, USA, Germany, and UK)
- Full auto-calendar function (until December 31, 2099)
- Time difference correction function
- Automatic needle position correction function
Both watches pair the dial with a titanium case and bracelet finished with a super-hard coating, a sapphire crystal with super-clear coating, and 10 bar water resistance. The SSH187 adds a ceramic/aluminum bezel; Seiko describes its crystal as dual-curved sapphire. Seiko’s SSJ039 page also notes a clasp with fine bracelet-length adjustment.
How their movements and functions differ
SSJ039: GPS Solar essentials
The SSJ039 uses Seiko caliber 3X62. Its listed functions include GPS time-zone and time adjustment, date, and a perpetual calendar that accounts for dates through February 28, 2100. Choose it if you want the smaller case and do not need the SSH187’s additional chronograph and timekeeping displays.
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- STUNNING BLUE DIAL: this automatic men's watch features a deep blue, pressed pattern and gloss finish surrounded by a stainless steel watch case
- AUTOMATIC: these self-winding, automatic men's watches are powered by your movement, with a power reserve of 41 hours
- STAINLESS STEEL: features a durable stainless steel watch case and bracelet with see through caseback
- WATER-RESISTANT: these men's wrist watches are water-resistant down to 50 meters
- 4R35 CALIBER: equipped with the reliable caliber 4R35 automatic movement, this accurate men's watch keeps precise time
SSH187: chronograph and expanded time displays
The SSH187 uses caliber 5X83. In addition to GPS time-zone and time adjustment, it has a chronograph that measures up to 12 hours in 1/20-second increments, dual time, world time for 38 cities, a day display, and a perpetual calendar through February 28, 2100. Its added functions come in a larger, thicker case.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Which should you choose?
- Choose the SSJ039 if the smaller listed dimensions matter more than extra complications. Seiko’s US listing shows it at USD 2,400.
- Choose the SSH187 if you want a chronograph, dual time and world time in the same GPS Solar watch, and are willing to consider the larger case. Seiko’s US listing shows it at USD 2,900.
This is a comparison of published specifications, not a hands-on assessment of comfort, legibility, durability in use or real-world GPS performance. Availability and pricing vary by market and may change. Seiko’s US pages use the references SSJ039J1 and SSH187J1, while the visible model headings omit the final “J1”; regional retailer references can also vary. UK boutique listings use the J1 suffix for both watches: SSJ039J1 and SSH187J1.
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Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
