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Astronomy  Primary mirror  Prime Meridian

prime focus The point in a reflecting telescope where the mirror focuses incoming light to a point.
primordial nucleosynthesis The production of elements heavier than hydrogen by nuclear fusion in the high temperatures and densities which existed in the early universe.

Prime Focus
The point at which an object mirror forms an image in a reflecting telescope
Primeval Atmosphere ...

Prime Focus
The focal point of the large primary reflecting mirror in astronomical telescopes when the light source is extremely distant.

Prime focus
In a prime focus design in large observatory telescopes, the observer sits inside the telescope, at the focal point of the reflected light. In the past this would be the astronomer himself, but nowadays CCD cameras are used.

Prime focus, barlow or variable projection.
Prime focus can work with most scopes
A barlow or Variable projection may NOT work depending on the scope's focuser travel.
Control image brightness and contrast by: ...

The location where light reflected from the primary mirror of a reflecting telescope comes into focus. Placing a secondary mirror in the light path allows the light to be focused elsewhere, in a more convenient location for the science instruments.
Primordial Nucleosynthesis ...

~ Photography - An astrographic technique in which a 35mm camera is positioned at a telescope's ~ - the focal plane of the primary mirror or objective lens. No eyepiece is used. Instead, the telescope and camera work together as a unit.

~ - (n.)
The location at which the main lens or mirror of a telescope focuses an image without being reflected or refocused by another mirror or other optical element.

Dish-shaped HGAs are the spacecraft antennas principally used for long-range communications with Earth.

~ primeval fireball high-powered explosion from a superhot, superdense state of condensed matter (the big band) that supposedly initiated the expansion of the Universe.

In a bid to answer the burning question of how galactic formation patterns become established and evolve, the research team led by Dr Yusei Koyama used the Subaru ~ Camera to make a panoramic observation of the rich galaxy cluster CL0939+4713, ...

Radio telescopes are mainly either ~ or Cassegrain reflectors. However, the radio telescope looks very different from the optical telescope; radio telescopes are much larger than optical telescopes.

The primary mirror reflects the light of the celestial object to the ~ near the upper end of the tube. Obviously, if an observer put his eye there to observe with a modest-sized reflector, he would block out the light from the primary mirror with his head.

As any instrument at the ~ will obstruct the light on its way towards the primary mirror, we can not put large instruments there.

Another view of the DSS-43 antenna showing the sub-reflector near ~ above the dish and the multiple primary feed system at the center of the dish.

The Lovell 76 metre telescope is a parabolic ~ dish named after the founding director of the Jodrell Bank Observatory, Sir Bernard Lovell. The observatory is owned and operated by the University of Manchester.

Until recently, astronomers actually sat in a cage at the ~ of the big mirror at the top of the telescope and stayed there all night to take images and spectra.

A class of reflecting telescope which uses a concave secondary mirror placed after the ~ is reached instead of a convex secondary placed before the ~. [McL97]
Gregorian Calendar ...

Reflecting telescopes (called "reflectors") come in five main configurations: ~, Newtonian, Cassegrain, Coudé, and Schmidt camera. The Ritchey-Chrétien design is also used.

MegaCam sits at the ~ of the CFHT, the Canada-France hawaii telescope, a 3.6 m optical telescope in Hawaii.
Cost: Professional-grade CCD chips are expensive.

The width of field (W) is found with: W = (57.3 x S) / F in degrees or 206265 S/F in seconds of arc, where S = film size and F = focal length of the telescope or camera lens. For example, using a 6' f/4 Newtonian at ~ the focal length will be 609.

See also: See also: What is the meaning of Telescope, Astro, Astronomy, Star, Planet?

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