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Topic: International Terrestrial Reference System

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	ICRS Narrative (Site not responding. Last check: 2007-11-04)
		Descriptions of reference frames and reference systems often refer to three coordinate axes, which are simply the set of right-handed cartesian axes that correspond to the usual celestial spherical coordinate system.
		The establishment of celestial reference systems is coordinated by the International Astronomical Union (IAU).
		The previous astronomical reference system was based on the equator and equinox of J2000.0 determined from observations of planetary motions, together with the IAU (1976) System of Astronomical Constants and related algorithms [1].
	aa.usno.navy.mil /faq/docs/ICRS_doc.html (4516 words)

	IERS Products: The International Terrestrial Reference System (ITRS)
		The International Terrestrial Reference System (ITRS) constitutes a set of prescriptions and conventions together with the modelling required to define origin, scale, orientation and time evolution of a Conventional Terrestrial Reference System (CTRS).
		The ITRS is an ideal reference system, as defined by the IUGG resolution No. 2 adopted in Vienna, 1991.
		The system is realised by the International Terrestrial Reference Frame (ITRF) based upon estimated coordinates and velocities of a set of stations observed by VLBI, LLR, GPS, SLR, and DORIS.
	www.iers.org /iers/products/itrs (186 words)

	International Celestial Reference System (Site not responding. Last check: 2007-11-04)
		At its 23rd General Assembly in August 1997, the International Astronomical Union (IAU) decided that, as from 1 January 1998, the IAU celestial reference system shall be the International Celestial Reference System (ICRS), in replacement of the FK5 (Fricke et al.
		By Reference System it is meant the set of prescriptions and conventions together with the modelling required to define at any time a triad of axes.
		Its origin is located at the barycenter of the solar system through appropriate modelling of VLBI observations in the framework of General Relativity.
	hpiers.obspm.fr /icrs-pc/icrs/Icrs.html (384 words)

	Global and European Reference Systems: Theory and Practice
		The reference frame of coordinates determined from point positioning will be identical to the reference frame of the satellite orbits, which is used to determine the satellite positions at signal emission time.
		The CTRS is geocentric and references north to the mean pole 1900-1905 and 0° longitude to the Greenwich Observatory, such as shown in Figure 1.
		The reference ellipsoid associated with recent ITRF is the Geodetic Reference System of 1980 (GRS80) ellipsoid (with a=6378137 m, 1/f=298.257222101 [13]).
	www.gps.oma.be /gb/refsys_gb_ok_css.htm (4755 words)

	International DORIS Service - Data Centers
		The International Earth rotation and Reference frames Service (IERS) has been established since 1988 jointly by the International Astronomical Union (IAU) and the International Union of Geodesy and Geophysics (IUGG).
		The IERS mission is to provide to the worldwide scientific and technical community reference values for Earth orientation parameters and reference realizations of internationally accepted celestial and terrestrial reference systems.
		In the geodetic terminology, a reference frame is a set of points with their coordinates (in the broad sense) which realize an ideal reference system.
	ids.cls.fr /html/data_centers.html (246 words)

	Canadian Spatial Reference System - Spatial Referencing - International Terrestrial Reference System
		This reference frame is used around the world to relate all other reference systems and datums.
		To relate the mean sea-level surface to the reference ellipsoid, a geoid model must be used.
		It approximates the variations in the height of mean sea level above the reference ellipsoid due to the irregular distribution of mass in the Earth.
	www.geod.nrcan.gc.ca /geodesy/reference/reference05_e.php (621 words)

	International Terrestrial Reference System - Wikipedia, the free encyclopedia
		The International Terrestrial Reference System (ITRS) describes procedures for creating reference frames suitable for use with measurements on or near the Earth's surface.
		The IERS defines a geocentric system of coordinates using the SI system of measurement.
		Practical navigation systems are in general referenced to a specific ITRF solution, or to their own coordinate systems which are then referenced to an ITRF solution.
	en.wikipedia.org /wiki/International_Terrestrial_Reference_System (203 words)

	North Pole (via CobWeb/3.1 planetlab2.isi.jhu.edu) (Site not responding. Last check: 2007-11-04)
		Astronomers define the North "geographic" Pole of a planet or other object in the solar system by the planetary Pole that is in the same ecliptic hemisphere as the Earth's North pole.
		It is desirable to tie the system of Earth coordinates (latitude, longitude, and elevations or orography) to fixed landforms.
		Yet the International Earth Rotation and Reference Systems Service and the International Astronomical Union have defined a framework called the International Terrestrial Reference System that does an admirable job.
	north-pole.iqnaut.net.cob-web.org:8888 (2066 words)

	AFREF
		Most countries in the world have established such reference systems that are used for national surveying, mapping, GIS and development programmes.
		Many of these national co-ordinate systems are based on reference figures of the Earth which are somewhat outdated and, when based on a local origin or datum point, are restricted to a particular country which makes cross-border or regional mapping, development and planning projects very difficult indeed.
		The establishment of a uniform geodetic reference system for any region or continent has wide ranging benefits in a variety of fields in which geospatial information is critical.
	w3sli.wcape.gov.za /SURVEYS/MAPPING/afref.htm (1145 words)

	EARTH ORIENTATION IN THE INTERNATIONAL REFERENCE SYSTEMS
		The nutation model and the rate corrections are referred to the mean pole at J2000.0.
		When IERS started operation in 1988, the EOP series were set in bias so as to be consistent with the initial realization of the International Terrestrial Reference System ITRS, the International Terrestrial Reference Frame ITRF_0, and with the ICRS.
		Each of them is referred to a celestial frame defined by the adopted Radio Source Coordinates (RSC) and to a terrestrial frame defined by the adopted Set of Station Coordinates (SSC).
	hpiers.obspm.fr /eop-pc/analysis/consistency.html (1251 words)

	UNB Professor played part in International Archeological dig
		Peter Dare joined the International Merv Project in Turkmenistan (North of Iran) to create a geodetic control network infrastructure connected to the International Terrestrial Reference System (ITRF) by use of International Global Positioning System Service (IGS) data.
		Although badly damaged in the Mongol invasion of 1218 A.D., Merv was restored and its prosperity re-established under the descendants of Tamerlane in the early fifteenth century.
		The International Merv Project was established by the Institute of Archaeology at University College London, England, has been visiting the archaeological site since 1992.
	www.unb.ca /bruns/0001/issue9/news/dig.html (596 words)

	[No title]
		Reigber The International Earth Rotation Service (IERS) was established in 1987 by IAU and IUGG and it started operation on 1988 January 1st.
		It replaces the International Polar Motion Service (IPMS) and the earth-rotation section of the Bureau International de l'Heure (BIH) ; the activities of BIH on time are continued at Bureau International des Poids et Mesures (BIPM).
		The results on earth rotation and reference frames are archived at the network and analysis centres which obtained them, as well as at the Central Bureau.
	www.gfy.ku.dk /~iag/iers95.txt (972 words)

	Earth Rotation and Equatorial Coordinates (via CobWeb/3.1 planetlab2.netlab.uky.edu) (Site not responding. Last check: 2007-11-04)
		In a sense, equatorial sky coordinates are a compromise between an earth-based system and one fixed with respect to distant stars.
		The reference planes are the equator, the Greenwich Meridian, and the plane through the earth's axis and perpendicular to the Greenwich Meridian, call it the east-west plane.
		Once an altitude/azimuth coordinate system is defined on the basis of celestial measurements, it can be defined to be consistent with coordinates as defined in three dimensions by VLBI or some other technique.
	www.cv.nrao.edu.cob-web.org:8888 /~rfisher/Ephemerides/earth_rot.html (2036 words)

	EUREF Permanent GPS Network > Tracking Network > Station Coordinates (via CobWeb/3.1 planetlab2.netlab.uky.edu) (Site not responding. Last check: 2007-11-04)
		It is also the system in which the precise IGS satellite orbits are given and it is the system from which other regional systems are derived.
		Supported by EuroGeographics, this reference system forms the backbone for all geographic and geodynamic projects on the European territory both on a national as on an international level.
		Throughout the years, each system had different realizations (or frames) which typically are an improvement with respect to the previous ones; more stations have been included and longer space geodetic observation periods are used in order to obtain more reliable station coordinates and velocities.
	www.epncb.oma.be.cob-web.org:8888 /_trackingnetwork/coordinates/stationcoordinates.php (572 words)

	Belgian Report of activity in the frame of the International Association of Geodesy
		Whenever one is processing data observed at terrestrial tracking stations, but coming from extra-terrestrial natural or artificial bodies, one has to link two reference systems: a terrestrial one and a celestial one.
		Precise knowledge of the Earth Rotation is thus needed for the connection of the reference systems.
		Therefore we participate in the International Comparison of Absolute Gravimeters (2001, Bureau International des Poids et Mesures) and in several bilateral comparisons in Belgium, France, Germany and Switzerland.
	iridia.ulb.ac.be /~hsaleh/IAGreportBelgium.html (7944 words)

	Polar motion - Wikipedia, the free encyclopedia (via CobWeb/3.1 planetlab2.isi.jhu.edu) (Site not responding. Last check: 2007-11-04)
		When using, instead of an inertial reference frame, a frame attached to the body of the solid Earth (a so-called Earth-centred, Earth-fixed or ECEF reference frame), the rotation axis also varies slightly.
		The latter are determined based on the International Terrestrial Reference System, which follows the polar motion.
		The slow westward drift, about 20 m since 1900, is partly due to motions in the Earth's core and mantle, and partly to the redistribution of water mass as the Greenland ice sheet melts, and to isostatic rebound, i.e.
	en.wikipedia.org.cob-web.org:8888 /wiki/Polar_motion (401 words)

	tani hosting tylko 3PLN! Profesjonalne i stabilne Serwery z PHP+MySQL, tanie domeny, serwer + domeny .plWeb Directory ... (Site not responding. Last check: 2007-11-04)
		International Earth Rotation Service (IERS) - Works to maintain the International Celestial Reference System and Frame, and the International Terrestrial Reference System and Frame, and to provide timely and accurate data on the Earth's orientation for current use and long-term studies.
		International Occultation Timing Association (IOTA) - was established to encourage and facilitate the observation of occultations and eclipses.
		The Webb Society - An international society of amateur and professional astronomers specialising in the observation of double stars and 'deep sky' objects, founded in 1967.
	www.goinfo.pl /dir/?c=Science/Astronomy/Associations (671 words)

	DORIS (Site not responding. Last check: 2007-11-04)
		The CNES (Centres Nationale d'Etudes Spatiales) in partnership with the IGN (Institut Geographique National), CLS and GRGS operate the DORIS System.
		It was designed to foster dialogue between IDS (International Doris Service) partners and DORIS system users in the fields of orbit determination and accurate location or applications relating to the field of gravity, modelling the ionosphere or troposphere and many more applications.
		DORIS is a Doppler satellite tracking system developed for precise orbit determination and precise ground location.
	www.env.gov.sc /html/doris.html (213 words)

	IGEX-98 Workshop Abstracts
		A by-product, the transformation between the ITRF reference system and the PZ-90 reference system, is obtained by comparing the precise orbit solution (in ITRF) and the broadcast orbit (in PZ-90) in an Earth-fixed system.
		The institute hopes for expansion of international communications and for fulfillment of the international projects on mutually advantageous conditions for all directions of geodetic and cartographic activity.
		Positive aspects were the efficiency of the centralized organization, the support from the international IGEX Network and the ability of a French MOD principal technical center to serve the scientific community.
	cddis.gsfc.nasa.gov /igex/igexws_abstracts.html (9246 words)

	[No title] (Site not responding. Last check: 2007-11-04)
		TEXT by Dave Doyle, NGS (10 May 2000) "NAD-83 vs WGS-84" Consider the relationship of the North American Datum1983 (NAD 83) coordinate system relative to it's relationship to earth-mass-center which is approximately 2 meters (3-dimensionally).
		This is commonly referred to as the International Terrestrial Reference Frame of 1994 (ITRF94).
		I would recommend that your "colleagues" read the series of articles on reference systems published by Dr. Richard Snay and Dr. Tomas Soler in Professional Surveyor Magazine, December 1999, February 2000 and March 2000.
	gpsinformation.net /main/ngs-accuracy.txt (468 words)

	International DORIS Service - About IDS (via CobWeb/3.1 planetlab2.isi.jhu.edu) (Site not responding. Last check: 2007-11-04)
		After a decade of fully operational functioning, the DORIS space geodesy system has demonstrated its capabilities for orbitography and navigation of the satellites and also ground location.
		DORIS and Laser are renewed as the nominal orbitographic system for the Jason mission (end of 2000).
		The CSTG, commission for international co-ordination of space techniques for geodesy of the International Association Geodesy (IAG) and the IERS directing board decided in July 1999 to initiate a DORIS Pilot Experiment.
	ids.cls.fr.cob-web.org:8888 /html/about_ids.html (348 words)

	North Pole - Wikipedia, the free encyclopedia (via CobWeb/3.1 planetlab2.isi.jhu.edu) (Site not responding. Last check: 2007-11-04)
		Most map coordinate systems are based on true north, and magnetic declination is often shown on map legends so that the direction of true north can be determined from north as indicated by a compass.
		The International Astronomical Union defines the geographic north pole of a planet or other object in the solar system as the planetary pole that is in the same ecliptic hemisphere as the Earth's North Pole.
		They rotate chaotically because of their irregular shape and gravitational influences from nearby planets and moons, and as a result the instantaneous pole wanders over their surface, and may vanish altogether for brief periods (when the object comes to a complete standstill with respect to the distant stars).
	en.wikipedia.org.cob-web.org:8888 /wiki/North_Pole (3310 words)

	007 (Site not responding. Last check: 2007-11-04)
		W0 ensures the consistency with the International Terrestrial Reference System.
		The scale of the International Terrestrial Reference Frame 2000 has also been specified with the use of W0 to be consistent with the Geocentric Coordinate Time.
		As an example of using W0 for a GVRS realization, the geopotential difference between the adopted W0 and the geopotential at the tide gauge point, specifying the North American Vertical Datum 1988, was determined.
	www.olympus.net /IAPSO/abstracts05/orals/007.html (282 words)

	[No title]
		Edge Response - The response of an imaging system to an edge target (i.e., a low/high or high/low step function), normalized so that the mean response on the low side of the edge target is set to zero and the mean response on the high side of the edge target is set to 100%.
		The inclusion of all these components allows a geodetic reference system to serve as a horizontal and vertical datum.
		The standard LDCM height reference is the surface of the WGS84 Earth ellipsoid.
	ldcm.nasa.gov /procurement/AcLex_FormPhaseRFP.doc (3880 words)

	[GRASS5] adding a new datum/projection? (Site not responding. Last check: 2007-11-04)
		For consistency with other GIS and because the International Terrestrial Reference System datum does not exist in the EPSG datum list, I added nzgd2k to the GRASS list.
		For now the transformations nzgd49 --> nzgd2k are still very accurate because we assume the gridshift file gives a transformation to wgs84, and then specify nzgd2k as having a zero shift relative to wgs84 (dx=dy=dz=0).
		It looks like transforming wgs84-->nzgd2k at high accuracy levels cannot really be done in the current GRASS/PROJ system because the relationship between nzgd2k and wgs84 is dynamic; assuming no difference between them should give acceptable results at small scales.
	grass.itc.it /pipermail/grass5/2003-July/008362.html (226 words)

	Welcome on ITRF web site
		The International Terrestrial Reference System (ITRS) is a world spatial reference System co-rotating with the Earth in its diurnal motion in space.
		The IERS, in charge of providing global references to the astronomical, geodetic and geophysical communities, promotes the realization of the ITRS.
		Realizations of the ITRS are produced by the IERS ITRS Product Center (ITRS-PC) under the name International Terrestrial Reference Frames (ITRF).
	itrf.ensg.ign.fr (185 words)

	The International Terrestrial Reference System (ITRS)
		The ITRS is realized by estimates of the coordinates and velocities of a set of stations observed by VLBI, LLR, GPS, SLR, and DORIS.
		Its name is International Terrestrial Reference Frame (ITRF).
		General documentation on terrestrial reference systems and frames is available at the ITRS Centre of the IERS.
	www.iers.org /iers/earth/itrs/itrs.html (174 words)

	Establishment of Absolute ITRF/WGS84 Coordinates in Dubai (Site not responding. Last check: 2007-11-04)
		In technical collaboration with the Institute of Applied Geodesy, Frankfurt, Germany, the Survey Section of Dubai Municipality executed a campaign for an Absolute GPS determination.
		As reference surface the WGS84 ellipsoid was chosen.
		To fit this ellipsoid to an absolute position, which was useful to monitor global plate tectonic movement measurements were taken to tie Dubai's local GPS network to the International Terrestrial Reference System ITRF, epoch 1993, which is determined globally by continous permanent tracking site.
	www.gisqatar.org.qa /conf97/links/p10_b3.html (235 words)

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