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	The Coronagraph in Space: Forecasting Solar Activity to Protect Transportation, Communication, and Power Supply on ...
		The coronagraph aboard this Solar and Heliospheric Observatory satellite is a dramatic breakthrough in NOAA space weather observers' ability to forecast the impact of coronal mass ejections on Earth.
		The coronagraph is a special type of telescope that uses a solid disk (known as an occulter disk) to block direct sunlight and create an artifical eclipse for the observer peering through the instrument.
		Inventing the coronagraph marked the beginning of systematic study of the Sun’s corona.
	celebrating200years.noaa.gov /breakthroughs/coronagraph/welcome.html (929 words)

	[No title] (Site not responding. Last check: )
		The coronagraph suppresses the diffracted light (diffraction spikes and rings) of the central source to below the level of the scattered light, most of which is caused by surface errors in the HST optics.
		The coronagraph was added after ACS construction began, at which point it was impossible to insert it into the aberration-corrected beam.
		Coronagraphic flats were taken during ground tests using an externally illuminated source and have been modified for application to on-orbit data (the spots shifted by about 1" during launch).
	www.stsci.edu:8082 /hst/acs/documents/handbooks/cycle12/c05_pol3.html?printable=1 (4534 words)

	Coronagraph -- Facts, Info, and Encyclopedia article (Site not responding. Last check: )
		The name comes from the fact that the first coronagraphs were used to image the ((botany) the trumpet shaped or cup shaped outgrowth of the corolla of a daffodil or narcissus flower) corona of the (A typical star that is the source of light and heat for the planets in the solar system) sun.
		Coronagraphs are useful for imaging coronas, near-solar ((astronomy) a relatively small extraterrestrial body consisting of a frozen mass that travels around the sun in a highly elliptical orbit) comets, and even (Click link for more info and facts about extrasolar planets) extrasolar planets.
		The coronagraph was introduced in 1930 by the (A physicist who studies astronomy) astronomer (Click link for more info and facts about Bernard Lyot) Bernard Lyot.
	www.absoluteastronomy.com /encyclopedia/c/co/coronagraph.htm (241 words)

	The Lyot Project
		A coronagraph is a device which blocks light from the center of the telescope beam while permitting light from surrounding sources to pass through relatively undisturbed.
		The coronagraph was invented by the French astronomer Bernard Lyot in 1939 (Figure 1), to enable astronomers to observe the hot gas (the corona) surrounding from the Sun without having to wait for total solar eclipses.
		The next stage of the coronagraph is the Lyot stop, which blocks out the remaining rings of light from the central star whilst allowing most of the light from surrounding sources to pass through to the final image, created by a final lens.
	www.lyotproject.org /background/coronagraphy.html (371 words)

	SPARTAN 201-3: Coronagraphs
		The externally occulted coronagraph uses an extra occulting disk which is placed in front of the first objective lens.
		The coronagraph was at that time used as part of a piece of military technology in an effort to predict atmospheric conditions affecting communications.
		A set of three coronagraphs, two in the externally occulted configuration, and one of a novel internally occulted design and using a mirror for an objective lens, will be launched into a unique high-altitude orbit on the SOHO spacecraft.
	umbra.gsfc.nasa.gov /spartan/coronagraphs.html (836 words)

	SPARTAN 201-3: Coronagraphs
		The externally occulted coronagraph uses an extra occulting disk which is placed in front of the first objective lens.
		The coronagraph was at that time used as part of a piece of military technology in an effort to predict atmospheric conditions affecting communications.
		A set of three coronagraphs, two in the externally occulted configuration, and one of a novel internally occulted design and using a mirror for an objective lens, will be launched into a unique high-altitude orbit on the SOHO spacecraft.
	umbra.nascom.nasa.gov /spartan/coronagraphs.html (836 words)

	ACS Handbook for Cycle 14 (Site not responding. Last check: )
		Because the coronagraphic masks are in place during acquisition, throughput is decreased by 52% relative to a non-coronagraphic observation.
		ACS coronagraphic flat fields are different from the standard flats due to the presence of the occulting spots and alteration of the field vignetting caused by the Lyot stop.
		To reduce the impact of spot motion, observers using the ACS coronagraph are required to obtain a reference PSF in an orbit immediately before or after their science observation.
	www.stsci.edu:8083 /hst/acs/documents/handbooks/cycle14/c05_pol3.html?printable=1 (5240 words)

	SPACE.com -- Double Vision: Two Telescopes for Hunting Earth-like Planets
		Initial designs for the space coronagraph, expected to be the first of the planet-hunting pair to launch, calls for a moderate-sized visible light telescope similar to a 13-foot by 20-foot (4-meter by 6 meter) mirror currently under study.
		The coronagraph would use a central disc, as well as other techniques, to blot out a star's glare, allowing the instrument to detect any planets that would otherwise be hard to spot.
		The coronagraph appears to be the easier of the two telescopes in terms of design, hence its earlier launch date.
	www.space.com /businesstechnology/technology/tpf_techwed_040526.html (1234 words)

	Coronagraphs (Site not responding. Last check: )
		LASCO actually contains three coronagraphs, each with a different sized occulting disk so that we can see the fainter and fainter corona, further and further away from the Sun's surface.
		It is possible to use coronagraphs from the top of a tall mountain on Earth as well, although you can't see the corona as far from the solar disk as you can in space.
		The image of a CME to the right is a composite made with data from both the SOHO/LASCO C2 and C3 coronagraphs.
	sohowww.nascom.nasa.gov /explore/coronagraph.html (354 words)

	coronagraph on Encyclopedia.com (Site not responding. Last check: )
		Because of the intense light of the sun, the corona and chromosphere can ordinarily be seen only during a total eclipse.
		The coronagraph consists of two refracting telescopes in tandem.
		A solid disk placed in front of the prime focus of the first telescope plays the part of the moon and eclipses the sun's image in the telescope so that only the outer layers of the sun's atmosphere are focused by the second telescope onto photographic film.
	www.encyclopedia.com /html/c1/coronagr.asp (250 words)

	JWST - Coronagraph (Site not responding. Last check: )
		A coronagraph is an instrument that blocks out the light from a bright object, enabling the viewer to detect the light from a fainter object nearby.
		The usual coronagraph is simply a dark spot that blots out the light from a bright object.
		MIRI's coronagraph still leaves a bright spot behind, but the brightness could be reduced by as much as a factor of a million.
	jwstsite.stsci.edu /reference_desk/coronagraph.shtml (257 words)

	Comet Champion of the Solar System
		The solid brick-colored disk in the middle is the coronagraph's occulting disk; the light red graphic circle shows the true size of the Sun.
		A coronagraph is a device that blocks out the Sun's blinding glare with an occulting disk so that the faint corona is visible, as well as surrounding stars and planets.
		Coronagraph images at the SOHO web site are updated every 30 minutes or so.
	science.nasa.gov /headlines/y2000/ast28aug_2.htm (1524 words)

	SPIE Bookstore
		Of the many novel coronagraphic and nulling techniques that have been suggested to improve image contrast for exoplanet detection, one of the most promising is the Quadrant Phase Mask suggested by Rouan et al.
		Coronagraphs for extra-solar planet detection remove diffracted stellar light through the combination of a coronagraphic mask and a Lyot stop.
		The principle of the nulling stellar coronagraph is to cause destructive interference for the light from a star.
	bookstore.spie.org /index.cfm?fuseaction=DetailVolume&productid=466451&showabstracts=1 (7347 words)

	The Lyot Project
		The Lyot Project's technical goal is to take Lyot's original invention, the coronagraph, to the physical diffraction limit, the limit imposed on a telescope's image resolution by the physics of light.
		The coronagraph will include numerous other components that are not shown in this photograph, and will be enclosed with a large metal case, to control airflow around the optics and to protect the system during shipment from New York to Maui.
		This device includes both a coronagraph (built at the American Museum of Natural History) and an infrared camera (which we call Kermit, built at the University of Hawaii and the University of California at Berkeley).
	www.lyotproject.org /description.html (485 words)

	The Lyot Project
		On March 3-5 2004, the coronagraph was shipped from the American Museum of Natural History in New York to the AEOS telescope in Maui, Hawaii.
		After five days of setup operations - installing the coronagraph at the observatory and integrating it with Kermit, the infrared camera - the system was working and ready for first light.
		This planet is about 4 Jupiter masses and so is likely to be too faint for our coronagraph to detect, but stars with known exoplanets are given high priority in our survey as they may well harbor planets or companions within our sensitivity range.
	www.lyot.org /results (444 words)

	What is a Coronagraph?
		A coronagraph is a telescope that can see things very close to the Sun.
		The Solar and Heliospheric Observatory (SOHO) has two coronagraphs onboard, one with a 3-degree field of view (the "C2" coronagraph) and another with a 16-degree field of view (the "C3" coronagraph).
		-- (Science@NASA) Using SOHO coronagraphs, amateur astronomers are discovering pieces of a giant comet that broke apart in antiquity as the fragments zoom perilously close to the Sun.
	www.spaceweather.com /glossary/coronagraph.html (188 words)

	NASM Space Artifacts: ATM Coronagraph
		The white light coronagraph was one of the principal ATM instruments for studying the sun's outer atmosphere, its corona.
		This white light coronagraph was one of the major instruments on board the Apollo Telescope Mount.
		The artifact consists of the flight demonstration verification unit (FDVU) for the ATM coronagraph.
	www.nasm.si.edu /research/dsh/artifacts/SS-coronagr.htm (570 words)

	CNN.com - Two telescopes better than one in space - May 26, 2004
		While the architectures of the coronagraph and interferometer versions are different, they can complement each other by giving researchers a more comprehensive look at extrasolar planets than any seen before.
		Initial designs for the space coronagraph, expected to be the first of the planet-hunting pair to launch, calls for a moderate-sized visible light telescope similar to a 13-foot by 20-foot mirror currently under study.
		The ability to design and build a set of telescopes capable of flying in formation while maintaining the precision and stability necessary for proper observations is a challenge, and researchers are working with their counterparts at the European Space Agency to meet the task.
	www.cnn.com /2004/TECH/space/05/26/telescopes.two (1049 words)

	LASCO/EIT Publications, 1995-1997
		The comparison of the computed and observed flux spectra are used to estimate the magnetic field strength at the base of the transition region and in the low corona, as well as the values of the conductive flux and the height of the base of the transition region.
		Among the primary science objectives assigned to the Lyot coronagraph are the determination of the mechanisms responsible for the acceleration of the solar wind and the heating of the corona.
		The middle coronagraph (1.5 R(solar radii) - 6 R(solar radii)) and the outer coronagraph (3 R(solar radii) - 30 R(solar radii)) are externally occulted lens Lyot coronagraphs.
	wwwsolar.nrl.navy.mil /sp_pubs_95-97.html (10175 words)

	SVI 23The Ultraviolet Coronagraph of the HERSCHEL experiment
		The Herschel (HElium Resonant Scattering in the Corona and HELiosphere) experiment, to be flown on a sounding rocket, will investigate the helium corona l abundance and the solar wind acceleration from a range of solar source structures by obtaining the first simultaneous observations of the electron, proton and helium solar corona.
		UVC is an imaging coronagraph that will image the solar corona from 1.4 to 4 solar radii in the EUV lines of HI 121.6 nm and the HeII 30.4 nm and in the visible broadband polarized brightness.
		The UVC coronagraph is externally occulted with a novel design as far as the stray light rejection is concerned.
	www.arcetri.astro.it /~solwind/abstract/node316.html (209 words)

	The Four-Quadrant Phase Mask Coronagraph. II. Simulations (ResearchIndex)
		2000) we have described the principle of a coronagraph utilizing a four-quadrant phase-mask and the results of numerical simulations obtained in the perfect case.
		The effect of geometrical parameters such as shape and size of both the phase-mask and the Lyot stop is studied.
		Astrometric Evidence that the Mass of the Companion to 16 Cyg..
	citeseer.ist.psu.edu /549509.html (163 words)

	Telescopes will double up on planet search - Space.com - MSNBC.com
		The first — a coronagraph — would blot out a star's light in the hopes of seeing small orbiting planets, while the other — an interferometer — would use a fleet of infrared telescopes working in tandem to hunt for the same extrasolar quarry.
		While the architectures of the coronagraph (TPF-C) and interferometer (TPF-I) versions of TPF are different, they can be used to complement each other and give researchers a more comprehensive look at extrasolar planets than any seen before.
		Initial designs for the space coronagraph, expected to be the first of the planet-hunting pair to launch, calls for a moderate-sized visible-light telescope similar to a 13-by-20-foot (4-by-6-meter) mirror currently under study.
	www.msnbc.msn.com /id/5069246 (1296 words)

	A Coronagraphic Search for Substellar Companions to Young Stars (Site not responding. Last check: )
		The coronagraph is actually a hole in one of the mirrors of the optical path and combined with a Lyot stop, reduces the amount of light in the Airy rings of the point spread function rather than merely blocking light.
		With the target behind the coronagraph, we reduce the amount of light at the edge of the coronagraph by a factor of 4-6 (figure 1) compared to direct imaging.
		The background flux is reduced by placing the star behind the coronagraph (dashed line), and reduced even more from the roll subtraction of two images (dotted line).
	ecf.hq.eso.org /nicmos/sardinia/lowrancep.html (1752 words)

	About LASCO (Site not responding. Last check: )
		The Large Angle and Spectrometric COronagraph (LASCO) instrument is one of 11 instruments included on the joint NASA/ESA SOHO (Solar and Heliospheric Observatory) spacecraft.
		The LASCO instrument is a set of three coronagraphs that image the solar corona from 1.1 to 32 solar radii.
		A coronagraph is a telescope that is designed to block light coming from the solar disk, in order to see the extremely faint emission from the region around the sun, called the corona.
	lasco-www.nrl.navy.mil /about_lasco.html (262 words)

	The Lyot Project
		Our coronagraph is designed specifically to operate within the 1.6 arcsecond radius from the star and as close as 0.2 arcseconds.
		In the case of the Lyot Project, the halo of light around the star is partially cleared to a radius of 1.6 arcsec at an imaging wavelength of 1.6 microns (the so-called infrared H band).
		This increase in sensitivity, through the Lyot Project's coronagraph, permits imaging of disks that are typical, with up to 100 times less dust than those which have already been observed.
	www.lyot.org /capabilities.html (691 words)

	coronagraph
		For good results, the objective lens must be superbly polished and be entirely free of internal defects such as striations or bubbles.
		Great care is taken to reduce scattered light by mounting a series of diaphragm stops inside the coronagraph tube.
		Observations need to be carried out under the most favorable atmospheric conditions—clean air being absolutely essential—so that coronagraphs are normally installed at high-altitude stations.
	www.daviddarling.info /encyclopedia/C/coronagraph.html (218 words)

	SPACE.com -- Solar Satellite Spots Otherwise Invisible Comet
		The coronagraph is able to see otherwise invisible outbursts from the Sun, such as coronal mass ejections and solar flares.
		The coronagraph is basically a blinder that blocks the glare of the Sun's surface.
		As a result, a very large volume of surrounding space became open to discovery since the craft's first observations in 1996.The coronagraph has enabled the most prolific discovery of comets in the history of astronomy.
	www.space.com /scienceastronomy/solarsystem/soho_comet_020108.html (492 words)

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