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Topic: Equatorial coordinates

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	Equatorial coordinate system - Wikipedia, the free encyclopedia
		It is the most closely related to the geographic coordinate system, because they use the same fundamental plane, and the same poles.
		Unlike longitude, right ascension is usually measured in hours instead of degrees, because the apparent rotation of the equatorial coordinate system is closely related to sidereal time and hour angle.
		The equatorial coordinate system is commonly used by telescopes equipped equatorial mounts by employing Setting circles.
	en.wikipedia.org /wiki/Equatorial_coordinates (426 words)

	Galactic coordinate system - Wikipedia, the free encyclopedia
		Galactic latitudes are measured in degrees and increase from 0° at the Galactic Equator to 90° at the North Galactic Pole near the star Arcturus and decrease to - 90° at the South Galactic Pole in the constellation Sculptor.
		Since galactic coordinates are spherical coordinates they do not define a specific point in the galaxy but rather a ray extending from the center of the galactic equator.
		The "zero of longitude" point on the galactic coordinates was calibrated to 17h45m37.224s, −28°56′10.23″ (J2000), and its J2000 position angle is 122.932°.
	en.wikipedia.org /wiki/Galactic_coordinate_system (924 words)

	10.4 PRECESS - Astronomical Coordinate Conversion
		The plane of zero declination is the projection of Earth's equator onto the celestial sphere, and the zero of RA is marked by the intersection of the ecliptic (Earth orbital) plane with the equatorial plane.
		While the coordinate system in most widespread use among astronomers is the B1950.0 system of equatorial coordinates, the IAU have recommended that J2000.0 coordinates be used.
		The system is defined in terms of B1950 equatorial coordinates as RA of (l=0) = 192.25 degrees, inclination of galactic equator to B1950 equator = 62.6 degrees, longitude of ascending node 33 degrees.
	ledas-cxc.star.le.ac.uk /udocs/docs/PG/html/node76.html (1449 words)

	telescope_system_commands2
		Equatorial coordinate systems differ in their equator and equinox which establish the reference plane and a particular fiducial point on it.
		Coordinate Files are text files which contain the celestial coordinates of objects to be observed and are an important aid to observational efficiency.
		These cause the Tracking Coordinates (current position of the telescope) or the Base Coordinates (the coordinates of the currently selected object) to be appended as a new record to the currently selected Coordinate File; see the description of the TRACK command in §1.3.
	msowww.anu.edu.au /observing/tcs_manual/celestial_coordinates.html (2981 words)

	Equitorial Coordinates
		The coordinates of the system form a sidereal (star) clock composed of 24 hours which is equal to the interval of one earth rotation.
		Using the equatorial coordinate system, we can specify the position of the individual stars on the surface of the celestial sphere just as the earth's system of latitude and longitude enables us to specify an individual's position on the surface of the earth.
		The altitude of a star is simply the angle between the star and the observer's horizon; and its azimuth is simply the angle between a point due north of the observer and the star, measured eastward along the horizon.
	www.astronomy.org /astronomy-survival/coord.html (1514 words)

	Astronomy - MSN Encarta
		Astronomers use coordinate systems to label the positions of objects in the sky, just as geographers use longitude and latitude to label the positions of objects on Earth.
		The equatorial coordinate system designates an object’s location with respect to Earth’s entire night sky, or the celestial sphere.
		In the equatorial coordinate system, the celestial sphere turns with the stars (but this movement is really caused by the rotation of Earth).
	encarta.msn.com /encnet/refpages/RefArticle.aspx?refid=1741502444&pn=5&s=40 (1317 words)

	TDDB28 Kursmaterial
		This gives rise to a new coordinate system whose plane is that of the galactic disk and whose reference longitude is the direction to the center of the Galaxy.
		Equatorial coordinates, which facilitate measurement and are therefore the most commonly used system, suffer from problems caused by variations in the Earth's rotation.
		All of the coordinate system and precession information for converting between coordinate systems (including Equatorial in either system), has been folded into the standard ADS Coordinate Conversion code and is available to be use in or as an adjunct to an service that wishes to do so.
	www.ida.liu.se /~TDDB28/mtrl/lab/astro_coord.sv.shtml (1729 words)

	Astro::Coord::ECI - Manipulate geocentric coordinates - search.cpan.org (Site not responding. Last check: 2007-10-24)
		The equatorial coordinates of the object are set to the results of the calculation, and the universal time of the object is set to the value of the $time argument.
		Equatorial coordinates are a spherical coordinate system referred to the plane of the equator projected onto the sky.
		It is defined in terms of the equatorial radius in kilometers, and a dimensionless flattening factor which is used to derive the polar radius, and defined such that the flattening factor of a sphere is zero.
	search.cpan.org /~wyant/Astro-satpass-0.005/ECI.pm (4366 words)

	Astronomical Leage - Astro Note 11: Celestial Coordinate Systems
		Although any arbitrary coordinate system could be used, these measurements are usually made in two specific systems by amateur astronomers.
		Coordinates are then specified by angular measure around the great circle from the reference point and by angular distance from the reference plane along another great circle perpendicular to that plane.
		Also called alt-azimuth or horizon coordinates, this system uses the plane of the local horizon as the plane of reference.
	www.astroleague.org /al/astrnote/astnot11.html (607 words)

	Earth Rotation and Equatorial Coordinates
		In practice, celestial coordinates are tied to observed objects because the location of the vernal equinox is hard to measure directly.
		Geodetic coordinates are a measure of the direction of the line perpendicular to the ideal ellipsoid at the observer's location on the earth.
		If geocentric coordinates for an observatory are not available directly they may be derived from geodetic coordinates using the equations given in ref [6].
	www.cv.nrao.edu /~rfisher/Ephemerides/earth_rot.html (2028 words)

	Equatorial Coordinates
		The horizon coordinate system (altitude and azimuth) is not convenient for specifying the location of celestial objects because the horizon coordinates of stars and other objects are continuously changing with time (due to the rotation of the Earth).
		An object's equatorial coordinates remain the same regardless of from where on Earth the object is viewed.
		The equatorial coordinate system used to specify the positions of celestial objects is directly analogous to the latitude-longitude coordinate system used on Earth.
	www.bisque.com /help/Patterns/patterns/equatorial_coordinates.htm (381 words)

	The Hipparcos Space Astrometry Mission: Selected Statistics from the Hipparcos and Tycho Catalogues
		The median relative precision of distance, sigma_pi/pi, for stars with a parallax pi >7.5 mas, in galactic coordinates.
		The median proper motion in declination, in equatorial coordinates.
		The systematic strucure is caused by the transformation from ecliptic to equatorial coordinates.
	www.rssd.esa.int /Hipparcos/vis_stat.html (846 words)

	Equatorial, Ecliptic and Galactic Coordinates (Site not responding. Last check: 2007-10-24)
		Source or event positions may be given in image pixels, sky pixels, detector pixels, equatorial coordinates right ascension (degrees) and declination (degrees), ecliptic longitude (degrees) and latitude (degrees) and galactic longitude (degrees) and latitude (degrees).
		Detector coordinates are specified with respect to the optical axis of the instrument.
		Equatorial, ecliptic and galactic coordinates have to be specified in degrees.
	wave.xray.mpe.mpg.de /exsas/users-guide/node116.html (1086 words)

	ccfind
		xrotation and yrotation are interpreted as the rotation of the ra / longitude and dec / latitude coordinates with respect to the x and y axes, and default 0.0 and 0.0 degrees respectively.
		The equatorial coordinate systems must be one of: 1) FK4, the mean place pre-IAU 1976 system, 2) FK4-NO-E, the same as FK4 but without the E-terms, 3) FK5, the mean place post-IAU 1976 system, 4) ICRS the International Celestial Reference System, 5) GAPPT, the geocentric apparent place in the post-IAU 1976 system.
		In both the above examples, x and y are the pixel coordinates, xi and eta are the usual projected (standard) coordinates, lng and lat are the celestial coordinates, and PROJ stands for the projection function, usually the tangent plane projection function.
	stsdas.stsci.edu /cgi-bin/gethelp.cgi?ccfind (2531 words)

	[No title] (Site not responding. Last check: 2007-10-24)
		The preset coordinates are for the observatory at Phoenix College in Arizona.
		Equatorial coordinates are plotted with respect to the rotation axis of the Earth.
		Equatorial coordinates consist of the right ascension (celestial longitude) abbreviated 'alpha' and declination (celestial latitude), 'delta'.
	chemlab.pc.maricopa.edu /hp/skydoc.txt (1539 words)

	3. Coordinate transformations (Site not responding. Last check: 2007-10-24)
		For equinox 2000, the coordinates of the north galactic pole are
		In ecliptic coordinates, for equinox 1950 the north galactic pole is at
		The relation between the two sets of coordinates, when describing the position of a field-of-view with respect to the sun, is shown in Fig.
	www.edpsciences.org /journal/index.cfm?v_url=aas/full/1998/01/ds1449/node3.html (667 words)

	[No title]
		Coordinates shall always be preceded by J for Julian 2000 equatorial coordinates, and should be preceded by G for galactic coordinates, or B for Besselian 1950 equatorial coordinates.
		Coordinates shall be truncated (not rounded), thus defining a unique (small) field on the sky in which the object is located.
		Coordinates used in designations shall be considered as names; therefore,they shall not be changed even if the positions change or become more accurately known (e.
	astro.u-strasbg.fr /old/iau.txt (751 words)

	AIPS HELP file (version 31DEC06) for SKYVE
		The DSS image coordinate system is encoded as a set of plate solution coefficients in FITS header cards which are not generally recognized by AIPS.
		COORDINATE SYSTEMS Coordinate transformations between the IAU1976 and Bessel-Newcomb systems are done with full precision assuming zero proper motion, parallax, and recessional velocity at J2000.0 Specifying a Julian epoch 'J' to SKYVE implies that the output coordinates are referenced to the new IAU1976/FK5 system.
		FK4 catalogue coordinates were not corrected for the elliptic terms of aberration (E-terms) except for positions within 10 degrees of the pole.
	www.aoc.nrao.edu /cgi-bin/aips/ZXHLP2.PL?SKYVE (1557 words)

	Equatorial, Ecliptic and Galactic Coordinates
		Source positions may be given in image pixels, sky pixels, detector pixels, equatorial coordinates right ascension (degrees) and declination (degrees), ecliptic longitude (degrees) and latitude (degrees) and galactic longitude (degrees) and latitude (degrees).
		Note:The coordinates have to be specified for equinox 2000.0.
		equatorial coordinates can be   precessed from any equinox to equinox 2000.
	www.atnf.csiro.au /computing/software/midas/Hypertext/exsasguide/exsasguidenode114.html (1041 words)

	Equatorial Coordinates
		equatorial coordinates." They take advantage of the fact that the stars' positions are nearly fixed with respect to a plane drawn through the earth's equator because the earth's axis points at the same part of the sky, the North Star Polaris, all year long.
		Still, these changes are so slow on the human time scale that we use the equatorial coordinates of stars to give their positions (in star catalogues) and to plot up star maps.
		It takes 26,000 years for precession to move the Vernal Equinox around the sky once; this means that precession changes the coordinates of stars by about 0.014 degrees/year or 8.4 arcminutes per century -- this fact is important only for pointing moderately large telescopes or identifying a really faint star.
	www.polaris.iastate.edu /NorthStar/Unit3/unit3_sub3.htm (481 words)

	Display 2: The Star Map and Equatorial Coordinates
		Equatorial lines are drawn, as well as the ecliptic and the boundary of the circumpolar region.
		RA/Decl coordinates may be entered using the Equatorial Coordinates dialog (similar to the Stonyhurst dialog, and obtained using the same top toolbar button).
		At the bottom of the star map is an information area displaying the current equatorial coordinates as well as the name of the target and its constellation, if relevant.
	www.solarphysics.kva.se /LaPalma/turret/node17.html (345 words)

	GETEPH
		The topocentric equatorial coordinates (J2000) of the object.
		The topocentric equatorial coordinates (J2000) of the heliocenter.
		The ecliptic coordinates (J2000) of the topocenter with respect to the barycenter.
	www.lowell.edu /users/buie/idl/geteph.html (2008 words)

	Coordinate Systems
		While the center of the grid for the horizontal system appears to be in the center of the sky, the center for the equatorial system is somewhere up towards the north, definitely off-center.
		The equatorial coordinate system is a fixed coordinate system, meaning the coordinates that describe the location of a star don't change with location on the Earth or with time.
		Equatorial coordinates make it much easier for astronomers to tell what star a person is referring to, since all stars have fixed coordinates.
	members.tripod.com /kjk176/coord_info.htm (888 words)

	Changes of Celestial Coordinates
		Precession of the Earth's polar axis is caused by the gravitational pull of the Sun and the Moon on the equatorial bulge of the flattened rotating Earth.
		While almost always unimportant for coordinate measurements, this effect is of vital importance for the determination of distances in the universe.
		When light passes from one medium to another medium of different density (e.g., from the vacuum to Earth's atmosphere), the speed of light in the medium is changed (light is slower in the denser medium), causing the wavelengths of light to bend at different angles.
	www.seds.org /~spider/spider/ScholarX/coord_ch.html (1035 words)

	[No title]
		If the user enters equatorial coordinates these are the galactic coordinates calculated from the user entered equatorial coordinates.
		If the user has entered equatorial coordinates (in PGA) these are the values entered by the user.
		If the user enters galactic coordinates these are the equatorial coordinates computed from the user entered galactic and precessed to the epoch entered by the user.
	www.iso.vilspa.esa.es /ida/pdm/icsa/TABLES_dbo.cam_coords.htm (379 words)

	Astronomical Coordinate Systems
		The coordinate systems considered here are all based at one reference point in space with respect to which the positions are measured, the origin of the reference frame (typically, the location of the observer, or the center of Earth, the Sun, or the Milky Way Galaxy).
		The major half axis represents the equatorial radius of the planet, while the minor axis is the polar (and thus the rotational) half axis, which is about 1/298 shorter than the equatorial radius.
		The second coordinate of a position in the horizon system is defined by the point where the verticle circle of the position cuts the horizon.
	www.seds.org /~spider/spider/ScholarX/coords.html#horiz (3777 words)

	HEASARC: Object Names/Coordinates Help
		Coordinates may be entered in the Equatorial, Galactic, and Ecliptic coordinate systems.
		The coordinates may be either decimal degrees or in sexagesimal format.
		As shown above, many of the above formats may be used in any coordinate system; however, the units of the longitude coordinate may depend upon the coordinate system if the syntax does not explicitly identify the units.
	starchild.gsfc.nasa.gov /Tools/name_or_coordinates_help.html (314 words)

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