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Topic: International Terrestrial Reference Frame

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	Frame of reference - Wikipedia, the free encyclopedia
		Alfred's frame of reference is considered an inertial frame of reference because he is not accelerating (ignoring effects such as Earth's rotation and gravity).
		Frames of reference are especially important in special relativity, because when a frame of reference is moving at some significant fraction of the speed of light, then the flow of time in that frame does not necessarily apply in another reference frame.
		An accelerated frame of reference is often delineated as being the "primed" frame, and all variables that are dependent on that frame are notated with primes, e.g.
	en.wikipedia.org /wiki/Frame_of_reference (1413 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.
		New ITRF solutions are produced every few years, using the latest mathematical and surveying techniques to attempt to realize the IERS as precisely as possible.
		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)

	[No title]
		The ITRS is specified in accordance with the resolutions of the International Union of Geodesy and Geophysics (IUGG), the International Association of Geodesy (IAG), and the International Astronomical Union (IAU).
		Since the ITRF should be as accurate as possible, and not merely stable from one realization to the next, care must be taken to ensure that the effects of systematic errors are identified and controlled to the extent possible.
		Specifications for the scale of the ITRF and its time evolution ================================================================== Background ---------- All of the techniques of the IERS are sensitive to the scale of the terrestrial frame at the several ppb (10^-9) level or better, where a 1 ppb scale error corresponds to an global station height error of 6.4 mm.
	hpiers.obspm.fr /eoppc/itrf/ITRF-WG.Report (5332 words)

	ITRF - GPS (Site not responding. Last check: 2007-10-25)
		The ITRF is established by the Terrestrial Reference Frame Section of the Central Bureau (CB) of the International Earth Rotation Service (IERS).
		The implementation of the ITRF is based on the combination of Sets of Station coordinates (SSC) and velocities derived from observations of space-geodetic techniques such as VLBI, LLR, SLR, GPS (since 1991) and DORIS (since 1994).
		In order to define a terrestrial reference frame, in a specific data analysis, four datum components (orientation, origin, scale and time evolution) should be clearly defined.
	lareg.ensg.ign.fr /CIAG/WITRF/ITRF-GPS.html (1374 words)

	2 Reference Frames and the Sagnac Effect (Site not responding. Last check: 2007-10-25)
		Although the ECEF frame is of primary interest for navigation, many physical processes (such as electromagnetic wave propagation) are simpler to describe in an inertial reference frame.
		In the ECEF frame used in the GPS, the unit of time is the SI second as realized by the clock ensemble of the U.S. Naval Observatory, and the unit of length is the SI meter.
		For example, from the inertial frame it appears that the reference clock from which the synchronization process starts is moving, requiring light to traverse a different path than it appears to traverse in the rotating frame.
	relativity.livingreviews.org /Articles/lrr-2003-1/node2.html (1337 words)

	Coordinate Reference Systems and Positioning - Wikibooks, collection of open-content textbooks
		In geodesy, a reference ellipsoid is a mathematically defined surface that approximates the true figure of the Earth or geoid.
		Mathematically, the reference ellipsoid is an oblate (flattened) ellipsoid of revolution with two different axes, an equatorial semi-major axis a and a polar semi-minor axis b.
		GRS80 was adopted by the International Union of Geodesy and Geophysics (IUGG) at its XVII General Assembly in Canberra, Australia, December 1979.
	en.wikibooks.org /wiki/Coordinate_Reference_Systems_and_Positioning (930 words)

	Ordnance Survey Ireland :: Geodetic services :: Overview :: GPS Reference Systems
		WGS84 is a geocentric reference ellipsoid and a geodetic datum, in that it defines the centre of mass of the earth as its origin, and the direction of the earth's axis as the minor axis of the reference ellipsoid.
		The high precision geodetic global reference frame is known as the International Terrestrial Reference Frame (ITRF), with positions expressed as three dimensional earth centred Cartesian co-ordinates.
		Thus different co-ordinate systems are established, within the defining reference frame, linked to the epoch of the observation, and transformations have been defined between them, which move positions from those determined at the time of observations to a common system at a defined epoch.
	www.osi.ie /gps/overview/gps.asp (918 words)

	Simek & Kostelecky
		In space geodetic positioning, where the observation techniques provide absolute positions with respect to a consistent terrestrial reference frame, the corresponding precise definition and realization of terrestrial and inertial reference systems is of fundamental importance.
		This model must be fitted to both the GPS reference frame and the levelling network co-defining the height system of the respective territory.
		The users may select the coordinate reference frame of their choice and input the relevant window coordinates or alternatively select an area from a geographic representation.
	www.fig.net /pub/proceedings/prague-final-papers/simek-kostelecky.htm (6128 words)

	Canadian Spatial Reference System - Guidelines - Reference Frame - ITRF
		The models that define the geocentric reference system along with the station coordinates and velocities used to realise the International Terrestrial Reference Frame currently give the best representation of the solid Earth and its time variations on a global scale.
		It is for that reason that the ITRF frame defined in terms of both coordinates and velocities is referenced to a specific epoch of time.
		The specific ITRF frame used by PPP is the one realised by IGS at the epoch for which the precise GPS orbits were computed.
	www.geod.nrcan.gc.ca /userguide/guideline/guideline4/guideline4b_e.php (198 words)

	[No title]
		Geodetic Reference Systems and Reference Frames Using the satellites orbiting around the Earth, the determination of geodetic positions became three-dimensional, either as rectangular (X, Y, Z) coordinates or converted to geodetic (latitude, longitude, ellipsoidal height) coordinates using an Earth-centered ellipsoid.
		When the International Terrestrial Reference Frame (ITRF) is specified in combination with a geocentric ellipsoid, such as the Geodetic Reference System (GRS) 1980 ellipsoid, then it is also a geodetic reference system.
		The original NAD 83 (86) reference frame has been retained throughout the years, even though that frame is not geocentric by about 2 meters.
	chartmaker.ncd.noaa.gov /bathytopo/DennisWeb/tutor.doc (3508 words)

	Positioning the Terrestrial Ephemeris Origin in the International Terrestrial Reference Frame
		Resolution B1.8 adopted by the XXIV General Assembly of the International Astronomical Union (Manchester, August 2000) recommends the use of the Non-Rotating Origin (Guinot 1979) on the moving equator both in the International Celestial Reference System (ICRS) and in the International Terrestrial Reference System (ITRS).
		Resolution B1.8 is to be implemented on 1 January 2003 by the International Earth Rotation Service (IERS) which is required to provide the position of the TEO in the ITRS.
		We propose then a numerical expression for the displacement of the TEO to be used in the new coordinate transformation from the Celestial Reference System to the Terrestrial Reference System according to the resolution.
	www.edpsciences.org /articles/aa/abs/2002/40/aa2747/aa2747.html (224 words)

	Geoscience Australia: Geodesy - Differences between coordinate systems
		It is based on the International Terrestrial Reference Frame 1992 (ITRF92) held fixed at 1 January 1994 — hence the name GDA94.
		To maintain consistency in Australia, accurate ITRF positions should be transformed to GDA94.
		This can be done using parameters based on the known GDA94 and continually updated ITRF positions of the Australian Regional GPS Network (ARGN).
	www.ga.gov.au /geodesy/datums/cosys.jsp (564 words)

	13th International Laser Ranging Workshop \| Scientific Achievements Session Summary (Site not responding. Last check: 2007-10-25)
		A clear and unique scientific study area is the global aspect of the terrestrial reference system, the implementation of which requires an absolute measure of origin and scale.
		Pavlis addressed the contributions of the laser ranging technique to the establishment of the terrestrial reference frame and, in particular, its origin component.
		The complementary global aspect of this frame, absolute scale, was discussed by Dunn, who highlighted historic developments and elaborated on recent achievements.
	cddis.gsfc.nasa.gov /lw13/lw_topic2sum.html (996 words)

	ITRF2000: A new release of the International Terrestrial Reference Frame for earth science applications
		For the first time in the history of the International Terrestrial Reference Frame, the ITRF2000 combines unconstrained space geodesy solutions that are free from any tectonic plate motion model.
		This new frame is the most extensive and accurate one ever developed, containing about 800 stations located at about 500 sites, with better distribution over the globe compared to past ITRF versions but still with more site concentration in western Europe and North America.
		Citation: Altamimi, Z. Sillard, and C. Boucher (2002), ITRF2000: A new release of the International Terrestrial Reference Frame for earth science applications, J.
	www.agu.org /pubs/crossref/2002/2001JB000561.shtml (417 words)

	THE ROTATING AND NON-ROTATING SET OF AXES (Site not responding. Last check: 2007-10-25)
		Hence we will choose as Oxyz axes the reference frame ITRF (International Terrestrial Reference Frame) that is more concretely related to the crust (Fig.
		6), with the same origin O. It is the geocentric equivalent of the reference frame ICRF (International Celestial Reference Frame; ARIAS et al.
		The relativistic corrections that are necessary between the barycentric ICRF and its geocentric version are negligible in the present study.
	geology.ref.ac /marchal/crf-trf.htm (269 words)

	Welcome on ITRF web site (Site not responding. Last check: 2007-10-25)
		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.
		You can also compute station positions and velocities in any ITRF version at any epoch and retrieve the solution in a SINEX file or a simple table.
	lareg.ensg.ign.fr /ITRF/solutions.html (185 words)

	Intraplate deformation in western Europe deduced from an analysis of the International Terrestrial Reference Frame 1997 ...
		Because of its accuracy and internal consistency at a global scale, the International Terrestrial Reference Frame 1997 (ITRF97) velocity field allows testing of intraplate rigidity in western Europe at a millimeter per year level.
		In this reference frame we find residual velocities at European ITRF sites that are consistent with known active tectonic features.
		Citation: Nocquet, J.-M. Calais, Z. Altamimi, P. Sillard, and C. Boucher (2001), Intraplate deformation in western Europe deduced from an analysis of the International Terrestrial Reference Frame 1997 (ITRF97) velocity field, J.
	www.agu.org /pubs/crossref/2001/2000JB900410.shtml (491 words)

	African Geodetic Reference Frame - AFREF
		The African Geodetic Reference Frame (AFREF) was conceived as a unified geodetic reference frame for Africa to be the fundamental basis for the national and regional three-dimensional reference networks fully consistent and homogeneous with the International Terrestrial Reference Frame (ITRF).
		ITRF is the global reference frame system for the earth as adopted by the International Association of Geodesy (IAG).
		When fully implemented, it will consist of a network of continuous permanent GPS stations such that a user anywhere in Africa would have free access to GPS data and products and would be at most 1000 km from such stations.
	geoinfo.uneca.org /afref (222 words)

	13th International Laser Ranging Workshop \| Overview Abstracts (Site not responding. Last check: 2007-10-25)
		Since the beginning of the ITRF activities in 1988, the Analysis Centers of the Satellite Laser Ranging (SLR) technique contributed significantly to the International Terrestrial Reference Frame (ITRF).
		Some aspects related to the optimal establishment of a global reference frame will be examined in case of SLR technique taking into account the reality of its current network configuration.
		Future ITRF directions will be presented and in particular the inclusion of Earth Orientation Parameters in the ITRF combination.
	cddis.gsfc.nasa.gov /lw13/archive/lw_topic1.html (154 words)

	Observational Strategies
		Beyond their scientific value, these data, together with precise determination of the 3-D geocenter motion by SLR and GPS, constitute the geodetic elements that define the International Terrestrial Reference Frame (ITRF), which is the basis for all geodetic measurements described in this report.
		The ITRF is geometrically connected to the Celestial Reference Frame via Earth Orientation Parameter (EOP) time series, which are determined primarily by the VLBI technique and contain a wealth of geophysical and climatic information.
		The ITRF and EOP, and hence the networks, should continue to be maintained and improved and their data routinely acquired at the best possible accuracy and temporal resolution.
	solidearth.jpl.nasa.gov /PAGES/pr_obs06.html (219 words)

	MM20 Feature - Machine Guidance
		However, there was a great deal of confusion between the International Terrestrial Reference Frame (ITRF), as provided by those international GPS processing services, and the Australian national datum, GDA94.
		The international component of the AUSPOS system is mediated by the division's membership of the International GPS service.
		The International Terrestrial Reference Frame (ITRF) produced by the International Earth Rotation Service (IERS) is a realisation of an ideal reference system based on the international terrestrial reference system.
	www.gisuser.com.au /MM/content/2002/MM20/feature_2/MM20_feature_2.html (1437 words)

	International DORIS Service - Terms of Reference
		A proof of concept for the International DORIS Service (IDS) was conducted through a Pilot phase until the establishment of the International DORIS Experiment in 1999 by the International Association of Geodesy (IAG).
		The IDS is an IAG Service and operates in close cooperation with the International Earth rotation and Reference frames Service (IERS).
		Changes in the IDS Terms of Reference and Chairperson of the GB can only be made by a 2/3 majority of the members of the GB, i.e., by six or more votes.
	ids.cls.fr /html/organization/tor.html (1631 words)

	ILRS Terms of Reference (Site not responding. Last check: 2007-10-25)
		The International Laser Ranging Service (ILRS) is an established Service within Section II, Advanced Space Technology, of the International Association of Geodesy (IAG).
		A proposal to amend the ILRS Terms of Reference can be made in writing to the Chairperson of the Governing Board (see Section 3.0) by any ILRS Associate Member (see Section 4.1).
		Changes in Terms of References and the Chairperson of the GB can be made by a 2/3 majority of the members of the GB, i.e., by twelve or more votes.
	ilrs.gsfc.nasa.gov /about_ilrs/termsref.html (3016 words)

	SC 1.3 Regional Reference Frames
		Sub-Commission 1.3 is concerned with definitions and realizations of regional reference frames and their connection to (and the densification of) the global International Terrestrial Reference Frame (ITRF).
		The main task of this WG is to develop harmonized and possibly common specifications for the regional reference frames implementation and ITRF densification.
		The regional reference frame activities are tied into the various IAG services through provision of data from individual sites to:
	iag.dgfi.badw.de /index.php?id=55 (178 words)

	421 (Site not responding. Last check: 2007-10-25)
		The contribution of ILRS to the International Terrestrial Reference Frame
		Satellite Laser Ranging (SLR) measurements to geodetic satellites (spherical, cannonball shape) provide unambiguous, straightforward, range observations from which the orbits of the satellites may be determined simultaneously with tracking station coordinates and velocities, Earth Orientation Parameters, gravitational harmonics, and a plethora of other parameters of geophysical interest.
		In these respects, the SLR role in maintenance of the ITRF is quite critical, and this role will continue as we look forward to the development of future issues of the ITRF in collaboration with the other geodetic services.
	www.olympus.net /IAPSO/abstracts05/orals/421.html (234 words)

	2001
		Angermann, D.: Realization of the International Terrestrial Reference Frame by DGFI Analysis Center.
		Proceedings of the First International Symposium on Robust Statistics and Fuzzy Techniques in Geodesy and GIS.
		Seemüller, W., K. Kaniuth, H. Drewes: Horizontal and vertical movements of the IGS regional reference network for South America.
	dgfi2.dgfi.badw-muenchen.de /index.php?id=55 (1316 words)

	GeodIS: IERS - International Earth Rotation Service
		Maintain the International Celestial Reference System and Frame and the International Terrestrial Reference System and Frame.
		International Celestial Reference Frame, ICRF (coordinates of extragalactic objects)
		International Terrestrial Reference Frame, ITRF94 (station coordinates & velocities)
	dgfi2.dgfi.badw-muenchen.de /typo3_geodis/index.php?id=47 (90 words)

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