40-foot Telescope
| Use attributes for filter ! | |
| First light | 19 February 1787 |
|---|---|
| Location(s) | Slough |
| Berkshire | |
| South East England | |
| England | |
| Focal length | 12 m (39 ft 4 in) |
| Diameter | 1. 2 m (3 ft 11 in) |
| Alternative names | Great Forty-Foot telescope |
| Telescope style | altazimuth mount; reflecting telescope |
| Date of Reg. | |
| Date of Upd. | |
| ID | 3049667 |
About 40-foot Telescope
William Herschel's 40-foot telescope, also known as the Great Forty-Foot telescope, was a reflecting telescope constructed between 1785 and 1789 at Observatory House in Slough, England. It used a 48-inch diameter primary mirror with a 40-foot-long focal length. It was the largest telescope in the world for 50 years.
