
	Where results make sense

Topic: Gregorian telescope

	Chapter Green Gown <i>to</i> Gregorian Telescope of G by Brewer's Phrase & Fable
		Gregorian Calendar One which shows the new and full moon, with the time of Easter and the movable feasts depending thereon.
		Gregorian Chant So called because it was introduced into the church service by Gregory the Great (600).
		Gregorian Telescope The first form of the reflecting telescope, invented by James Gregory, professor of mathematics in the university of St. Andrews.
	www.bibliomania.com /2/3/255/1172/22850/3.html (318 words)

	Telescope - LoveToKnow 1911
		His first telescope magnified three diameters; but he soon made instruments which magnified eight diameters, and finally one that magnified thirty-three diameters.' With this last instrument he discovered in 1610 the satellites of Jupiter, and soon afterwards the spots on the sun, the phases of Venus, and the hills and valleys on the moon.
		telescope of the Lick Observatory at Mount Hamilton, California, Grubb suggested that the whole floor, 70 ft. in diameter, should be raised and lowered by water power, under control of the observer by means of electric keys which act on secondary mechanism that in turn works the valves and reversing gear of the water engines.
		The ob j ect-glass of the telescope is, of course, attached by its cell to the upper end of the telescope tube.
	www.1911encyclopedia.org /Telescope (13683 words)

	telescope from On-line Medical Dictionary
		Astronomical telescope, a telescope which has a simple eyepiece so constructed or used as not to reverse the image formed by the object glass, and consequently exhibits objects inverted, which is not a hindrance in astronomical observations.
		Galilean telescope, a refracting telescope in which the eyeglass is a concave instead of a convex lens, as in the common opera glass.
		Herschelian telescope, a reflecting telescope of the form invented by Sir William Herschel, in which only one speculum is employed, by means of which an image of the object is formed near one side of the open end of the tube, and to this the eyeglass is applied directly.
	cancerweb.ncl.ac.uk /cgi-bin/omd?telescope (428 words)

	Definition of Gregorian Calendar from dictionary.net
		Gregorian calendar, the calendar as reformed by Pope Gregory XIII.
		Gregorian chant (Mus.), plain song, or canto fermo, a kind of unisonous music, according to the eight celebrated church modes, as arranged and prescribed by Pope Gregory I. (called ``the Great'') in the 6th century.
		Gregorian telescope (Opt.), a form of reflecting telescope, named from Prof.
	www.dictionary.net /gregorian+calendar (388 words)

	Gregorian telescope
		An early type of reflecting telescope, designed by the Scottish mathematician and astronomer James Gregory (1638-1675), that uses two curved mirrors: a concave paraboloidal primary and a concave ellipsoidal secondary.
		Although the Gregorian is free from chromatic and spherical aberration, it requires a long telescope tube.
		It was rendered obsolete by the Cassegrain telescope.
	www.daviddarling.info /encyclopedia/G/Gregorian_telescope.html (172 words)

	Telescope - definition from Biology-Online.org (Site not responding. Last check: )
		Cassegrainian telescope, a reflecting telescope invented by Cassegrain, which differs from the gregorian only in having the secondary speculum convex instead of concave, and placed nearer the large speculum.
		Reflecting telescope, a telescope in which the image is formed by a speculum or mirror (or usually by two speculums, a large one at the lower end of the telescope, and the smaller one near the open end) instead of an object glass.
		Refracting telescope, a telescope in which the image is formed by refraction through an object glass.
	www.biology-online.org /dictionary/Telescope (498 words)

	Home Page
		The ability to adapt a heliometer to an existing telescope has caused some concern as to exactly how this was done, inasmuch as the heliometer objective requires at least some small amount of optical power in order to function, thereby altering the overall focal length of the telescope.
		Considering the overall effective focal length of a Gregorian and the large amplifying power of the secondary mirror, it becomes apparent that the introduction of even a slight amount of optical power at the front end of the instrument would cause the focal plane at the eyepiece to change by several inches.
		However, Short's Gregorians were focused by moving the secondary mirror and not by the focuser at the eyepiece.
	www.rfroyce.com /short (1266 words)

	Tiverton A.S. \| Telescopes
		At the simplest level, all reflecting telescopes involve the use of mirrors to focus light rays (and lenses at the eyepiece), whereas refracting telescopes rely purely upon lenses.
		In the 'aplanatic' Gregorian, coma effects and spherical aberration are eliminated because it uses an ellipsoid primary.
		Any telescope in which light emerges along the polar axis; this means direction is fixed as the observed object follows its path across the sky.
	www.tivas.org.uk /socsite/scopes.html (657 words)

	GREGORIAN - Definition
		{Gregorian chant} (Mus.), plain song, or canto fermo, a kind of unisonous music, according to the eight celebrated church modes, as arranged and prescribed by Pope Gregory I.
		A small concave mirror in the axis of this telescope, having its focus coincident with that of the large reflector, transmits the light received from the latter back through a hole in its center to the eyepiece placed behind it.
		Thus, every year, of the current reckoning, which is divisible by 4, except those divisible by 100 and not by 400, has 366 days; all other years have 365 days.
	www.hyperdictionary.com /dictionary/gregorian (258 words)

	UA-93-02: The Gregorian Question
		The telescope tube length is set by the mechanical lever arm for the secondary attachment, rather than by the position of the secondary itself.
		The Gregorian secondary increases the height of the dome by 1 to 1.5 meters.
		In this case, an inverted Gregorian F/5.25 collimator with a 0.325 meter ~ F/2.7 primary matches the 2.1 meter radius of curvature of the telescope.
	medusa.as.arizona.edu /lbto/tech/ua9302.htm (3389 words)

	John Pierce's Telescope Making Articles.
		With the Newtonian or Herschellian telescope, the images formed by the mirror is viewed through the eyepiece; the total magnification being equal to the quotient obtained when the focal length of the mirror is divided by the focal length of the eyepiece.
		Two methods are possible; one by using a second concave mirror as in the Gregorian telescope; the other by using a convex mirror as in the Cassegrain telescope.
		If we allow the telescope tube to project 6 inches beyond the secondary mirror, the total length of the telescope would be only 73 1/2 inch, instead of the 20 foot length needed for a Newtonian of the same power.
	bobmay.astronomy.net /johnpierce/part9.htm (2872 words)

	Gregorian telescope by Adams
		One of the most imposing exhibits in the History Museum of Tartu University is a four-inch Gregorian telescope.
		The telescope was purchased in 1805 and it was constructed most probably at the end of the previous century.
		The telescope is made of brass only, with rounded handles of polished wood for precise regulation.
	www.ut.ee /REAM/Telescope.htm (285 words)

	A Glossary for Telescope Buyers and Users
		In telescopes which have a diagonal mirror or a secondary mirror so positioned as to obstruct part of the incoming beam of light, the presence of that obstruction reduces the contrast of the image somewhat.
		Thus, a telescope with a clear aperture of 150 mm, having an obstruction that is 50 mm in diameter, experiences the same loss of contrast whether we report the obstruction as 0.33 (ratio of diameters) or 0.11 (ratio of areas).
		A Cassegrain configuration telescope whose optics consist of a concave primary mirror, which is spherical in most of the common commercial designs, a full-aperture Schmidt corrector plate mounted near the focal point of the mirror, and a small, convex secondary mirror positioned in the converging beam, as in a true Cassegrain.
	observers.org /beginner/glossary.html (11783 words)

	Gregorian Telescope
		The form of reflecting telescope suggested by James Gregory (1638-1675) predates the familiar form of reflector which Isaac Newton (1642-1727) first designed and made in 1668.
		The problem with the reflecting telescope is how to view the image formed by the primary mirror.
		Other examples of refracting telescopes may be found in the Optics section.
	physics.kenyon.edu /EarlyApparatus/Astronomy/Gregorian_Telescope/Gregorian_Telescope.html (187 words)

	Charles Messier's Original Catalog of 1771
		That nebula which I have examined with a Gregorian telescope of 30 pouces focal length, which magnifies 104 times, doesn't contain any star; the center is brilliant, and the light gets lost fading [outward]; it is round, and could have 3 minutes of arc in diameter.
		When having examined that nebula with a Gregorian telescope of 30 pouces which magnified 104 times, I have not seen any star there: it is round and beautiful, its diameter is about 4 minutes of arc; one sees it difficultly with an ordinary [non-achromatic] refractor of one foot [FL].
		I have examined it with a Gregorian telescope which magnified 104 times: it appears in an oval shape; it doesn't contain any star; its diameter is about 4 minutes of arc.
	www.seds.org /MESSIER/xtra/history/m-cat71.html (5399 words)

	The ATM Page - Telescope Design - Gregorian (Site not responding. Last check: )
		The first experiments with reflecting telescopes were begun in 1639, but it wasn't until 1663 that a practical design was proposed.
		As a result of the dismal performance of the first prototypes, this design was virtually forgotten for the next 60 years.
		In the mid 1700's the Gregorian became the most popular design for both professional and amateur astonomers, in part because it produced an erect image.
	www.earlham.edu /~rodrimi/Gregorian.htm (222 words)

	ScienceDaily: Astronomy
		Astronomers Find Sun's Coolest Neighbors (June 3, 1999) -- A pair of near-infrared telescopes sponsored by NASA and the National Science Foundation has detected the coolest brown dwarfs ever seen -- celestial objects that are neither fish nor fowl, or in...
		University Of Minnesota Researcher Focuses New Space Telescope (April 4, 2003) -- Suppose you had to focus a pair of binoculars blindfolded--and if you failed, a 0 million investment would be lost in space.
		Radio telescope -- A radio telescope is a form of radio receiver used in astronomy.
	www.sciencedaily.com /encyclopedia/astronomy (1406 words)

	Gregorian telescope (NAV1590) - National Maritime Museum
		This small brass telescope is a reflecting telescope that uses a curved mirror rather than an objective lens to collect light and produce the observed image.
		He subsequently became the most successful London manufacturer of Gregorian telescopes, which were named after their original inventor.
		A Gregorian telescope is a type of reflecting telescope invented by James Gregory (1638-1675) in 1663.
	www.nmm.ac.uk /collections/explore/object.cfm?ID=NAV1590 (151 words)

	SORL - Telescopes
		A Gregorian telescope, employing a concave parabolic secondary mirror is sometimes used in combination with a pinhole placed at the common focus to "spatially filter" the laser beam.
		In most telescope applications it is desired that light from a distant object or source be brought to focus where it may be detected, photographed, or measured.
		In the Newtonian Telescope, a small diagonal mirror is inserted in the focusing beam to bring it out at a right angle to the incoming beam.
	www.sorl.com /productline/telescopes/telescopes/telescopes.htm (1249 words)

	twatkins5038 (Site not responding. Last check: )
		Telescopes of this type were often stamped on the mirror with the makers initials.
		The telescope attaches to the base with two brass wing nuts.
		Browse, R.N.” This is a classic example of 18th century Gregorian telescope so prevalent in England at that time.
	www.arsmachina.com /t-watkins5038.htm (208 words)

	First Call for Observing Proposals using the Arecibo Gregorian System (Site not responding. Last check: )
		This is a call for proposals to use the telescope during its commissioning period.
		The telescope pointing and calibration, equipment performance, monitor and control software, etc., should be at a reasonable level of performance, and adequately documented, by the time that the first telescope users commence their observations.
		Outside users scheduled during these first months are expected to share the expertise they gain with the staff, and especially to furnish written reports of any experiences or calibrations that will be of use to the staff in preparing for normal operations.
	www.naic.edu /public/about/newslett/nov97/number23-3.html (716 words)

	Why Offset Gregorian?
		A 10 meter telescope operating at 200 microns wavelength has a diffraction-limited beam, and diffraction effects will tend to dominate the classical optical aberrations such as coma and astigmatism.
		Dragone has shown that if the offset angles in an offset Gregorian antenna are chosen correctly, then aberrations and cross-polarization effects in an offset antenna are the same as those in a conventional on-axis antenna with the same diameter and focal length.
		An offset telescope allows for large prime-focus instrument packages of the type used successfully on PYTHON and other CMBR telescopes; these instruments cannot be used with an on-axis design.
	www.cfa.harvard.edu /~aas/SPT/gregorian.htm (331 words)

	Gregorian telescope (Site not responding. Last check: )
		An optical instrument used in astronomy for observing distant objects.
		Any instrument used in astronomy for observing distant objects (such as a radio telescope).
		It uses material from the Wiktionary page "Telescope".
	www.serebella.com /encyclopedia/article-Gregorian_telescope.html (126 words)

	fSONA: The Company
		The compact telescope is derived from a standard Gregorian system by flipping the secondary mirror over a folding mirror in the middle of the optical path between the primary and secondary mirrors.
		The result is a Compact Gregorian Telescope that can be as short as 1/7th the focal length of the system.
		Although the Gregorian telescope was first developed in the 17th century, a Compact Gregorian Telescope was not possible until recently when techniques for producing diamond-turned mirrors were readily available.
	www.fsona.com /company.php?sec=pr_mar302004 (535 words)

	Figure: Gregorian reflecting telescope (1663)
		Long before the technology existed to make it, James Gregory envisioned a telescope with a parabolic primary mirror.
		The telescope’s images would have been free of both chromatic and spherical aberration.
		The mirror's shape was parabolic, not spherical, eliminating spherical aberration.
	amazing-space.stsci.edu /resources/explorations/groundup/lesson/basics/g10b/index.php (53 words)

	Chapter Green Gown <i>to</i> Gregorian Telescope of G by Brewer's Phrase & Fable
		Chapter Green Gown to Gregorian Telescope of G by Brewer's Phrase and Fable
		To "give one a green gown" sometimes means to go beyond the bounds of innocent playfulness.
		Copyright: All texts on Bibliomania are © Bibliomania.com Ltd, and may not be reproduced in any form without our written permission.
	www.bibliomania.com /2/3/255/1172/22850/1.html (522 words)

	Photonics.com Printer Friendly View (Site not responding. Last check: )
		fSONA said the compact telescope involves flipping the secondary mirror over a folding mirror in the middle of the optical path between the primary and secondary mirrors.
		The result is a compact Gregorian telescope that can be as short as 1/7th the focal length of the system.
		The Gregorian telescope was first developed in the 17th century, but a compact version was not possible until techniques for producing diamond-turned mirrors became readily available, fSONA said.
	www.photonics.com /printerFriendly.aspx?contentID=62089 (195 words)

Try your search on: Qwika (all wikis)