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Gregorian secondary mirror
A circular concave mirror made as a secondary mirror for a Gregorian telescope. This secondary mirror has a brass mount and a diameter of 1.4 inches (35.56mm). It has a moderate polish and no cover.
A Gregorian telescope typically has two mirrors - a large circular concave mirror with a hole in the middle called a primary mirror, this mirror is used to collect light from the distant object being viewed, and a small circular concave mirror known as a secondary mirror. for reflecting the light collected into the eyepiece. The hole in the middle of the primary mirror is there so the light can get from the secondary mirror to the eyepiece through the primary mirror. William Herschel made and used Gregorian telescopes before moving on to Newtonian and later Herschelian (to his own design) telescopes.
A Gregorian telescope typically has two mirrors - a large circular concave mirror with a hole in the middle called a primary mirror, this mirror is used to collect light from the distant object being viewed, and a small circular concave mirror known as a secondary mirror. for reflecting the light collected into the eyepiece. The hole in the middle of the primary mirror is there so the light can get from the secondary mirror to the eyepiece through the primary mirror. William Herschel made and used Gregorian telescopes before moving on to Newtonian and later Herschelian (to his own design) telescopes.
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Object Details
| ID: | AST0829 |
|---|---|
| Collection: | Astronomical and navigational instruments |
| Type: | Gregorian secondary mirror |
| Display location: | Not on display |
| Creator: | Herschel, William |
| Date made: | circa 1800 |
| People: | Herschel, William |
| Credit: | National Maritime Museum, Greenwich, London, Herschel Collection |
| Measurements: | Overall: 23 mm x 35.5 mm; Diameter: 35.56 mm |