The Seiko Astronomical Observatory Chronometer 4520-8020 (ref. 45GSN 016) is a Hi-Beat manual wind watch.
The Neuchâtel observatory certified a total of 226 caliber 4520A sent by Daini Seikosha between 1968 and 1970, making the Astronomical Observatory Chronometer one of the rarest vintage Seiko watches.
18k Gold
| Ref. | 45GSN 016 |
| Case-movement ref. | 4520-8020 |
| Year | 1970 |
| Retail price | ¥180,000 |
| Caliber | 4520A |
| Jewels | 25 |
| Bph | 36,000 |
| Type | Hi-Beat Manual Wind |
| Family | 45GS |
| Branch | Daini Seikosha |
| Material | 18k Gold |
| Crystal | Acrylic |
| Size | Diameter: 36 mm Lug width: 18 mm |
| Complications | – |
| Hacking | Yes |
| Dial code | JAPAN 4520-8020T |
| Technical info | Japanese |
| Catalogs |