Comet seeker

A comet seeker telescope is a type of optical device that is known for having a short focal length but a wide field of view.

[2] A comet seeker with about 3.9 inch aperture was installed at the United States Naval Observatory in 1843, and later transferred to the Smithsonian Museum in 1866.

[3] This was operated as part of suite of several other instruments including a larger refractor on an equatorial mounting, a meridian transit, mural circle, etc.

[5] An 8.6-centimetre (3.4 in) aperture Comet Seeker was used, with some customizations, to produce the Bonner Durchmusterung star catalog from Bonn Observatory, in the 19th century.

[6] In 1866 a Comet Seeker telescope of 18 centimetres (7.1 in) aperture by Martin was acquired by the Marseille Observatory in France.

Comet seeker telescope, Helsinki observatory. Made by Utzschneider and Fraunhofer in 1830s.
A comet closeup, visited by a probe in the early 21st century
A comet as seen from Earth