A comet seeker is a type of small
telescope
A telescope is a device used to observe distant objects by their emission, Absorption (electromagnetic radiation), absorption, or Reflection (physics), reflection of electromagnetic radiation. Originally, it was an optical instrument using len ...
adapted especially to searching for
comet
A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...
s: commonly of short
focal length
The focal length of an Optics, optical system is a measure of how strongly the system converges or diverges light; it is the Multiplicative inverse, inverse of the system's optical power. A positive focal length indicates that a system Converge ...
and large
aperture
In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...
, in order to secure the greatest brilliancy of
light
Light, visible light, or visible radiation is electromagnetic radiation that can be visual perception, perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400– ...
. This style of telescope was used to discover the asteroid
9 Metis
9 Metis is one of the larger main-belt asteroids. It is composed of silicates and metallic nickel-iron, and may be the core remnant of a large asteroid that was destroyed by an ancient collision. Metis is estimated to contain just under half a ...
in 1848.
Design
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.
Examples
A comet seeker with about 3.9 inch aperture was installed at the
United States Naval Observatory
The United States Naval Observatory (USNO) is a scientific and military facility that produces geopositioning, navigation and timekeeping data for the United States Navy and the United States Department of Defense. Established in 1830 as the ...
in 1843, and later transferred to the Smithsonian Museum in 1866.
It had an aperture of 4 inches (10.2 cm) and was made by Utzschneider & Fraunhofer in Munich.
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.
added a 3-inch aperture Comet Seeker on an equatorial mount by Ertel.
It was ordered in 1842, and in place until 1874.
The Markree Comet Seeker was used to discover
9 Metis
9 Metis is one of the larger main-belt asteroids. It is composed of silicates and metallic nickel-iron, and may be the core remnant of a large asteroid that was destroyed by an ancient collision. Metis is estimated to contain just under half a ...
in April 1848.
It was discovered by Edward Cooper's assistant Andrew Graham, who worked at that observatory until 1860.
Graham also observed and sketched the
Orion nebula
The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula in the Milky Way situated south of Orion's Belt in the Orion (constellation), constellation of Orion, and is known as the middle "star" in the "sword" of Orion. It ...
with this Ertel Comet seeker.
An aperture Comet Seeker was used, with some customizations, to produce the
Bonner Durchmusterung
In astronomy, Durchmusterung or Bonner Durchmusterung (BD) is an astrometric star catalogue of the whole sky, published by the Bonn Observatory in Germany from 1859 to 1863, with an extension published in Bonn in 1886. The name comes from ('run-t ...
star catalog from
Bonn Observatory, in the 19th century.
In 1866 a Comet Seeker telescope of aperture by Martin was acquired by the
Marseille Observatory in France.
See also
*
List of telescope types
*
List of largest optical telescopes in the 19th century
*
Lists of comets
Non-periodic comets are seen only once. They are usually on near-parabolic orbits that will not return to the vicinity of the Sun for thousands of years, if ever.
Periodic comets usually have elongated elliptical orbits, and usually return to th ...
References
External links
Photograph of comet seeker telescope used in the Lick Observatory circa 1893 from the Lick Observatory Records Digital Archive, UC Santa Cruz Library's Digital Collections{{Webarchive, url=https://web.archive.org/web/20191001175644/http://digitalcollections.ucsc.edu/cdm/singleitem/collection/p265101coll10/id/710/rec/1 , date=2019-10-01
Telescopes