scholarly journals Project MERIT and the Formation of the International Earth Rotation Service

2000 ◽  
Vol 178 ◽  
pp. 187-200 ◽  
Author(s):  
G.A. Wilkins
Keyword(s):  
Earth Rotation ◽  
Terrestrial Reference Frame ◽  
International Earth Rotation Service ◽  
International Earth Rotation ◽  
International Astronomical ◽  
International Programme ◽  
Earth Rotation Parameters ◽  
Set Up ◽  
Additional Support ◽  
Comparison Of The Results

AbstractProject MERIT was an international programme to Monitor Earth Rotation and Intercompare the Techniques of observation and analysis. It was conceived by a working group that was set up by the International Astronomical Union in 1978 and was carried through with additional support from the International Union of Geodesy and Geophysics. The first objective was to encourage the development of the use of new techniques, such as laser ranging and radio interferometry, for the regular determination of universal time and polar motion. A successful ‘short campaign’ of observations by six techniques was carried out during the period 1980 August to October. Operational and analysis centres were set up for each technique and a coordinating centre was established at the Bureau International de l’Heure (BIH). The results were reported and discussed at the first MERIT Workshop in 1981.The preparations for the ‘main campaign’, which was held from 1983 September 1 to 1984 October 31, and the plans for the activities that were to follow it were reviewed at the second MERIT Workshop in 1983. Important additional features of the campaign included the use of ‘MERIT Standards’ for the reduction and analysis of the data, the use of electronic techniques for the distribution of data, the comparison of the results with the changes in the angular momentum of the atmosphere and special emphasis on the improvement of the terrestrial reference frame. Proposals for a new International Earth Rotation Service were prepared at the third MERIT Workshop in 1986. The MERIT programme was continued from 1984 until the new service formally started on 1988 January 1. Over the decade the accuracy of the Earth-rotation parameters improved considerably.

scholarly journals SLR Contribution to Investigation of Polar Motion

2000 ◽  
Vol 178 ◽  
pp. 267-276
Author(s):  
Zinovy Malkin
Keyword(s):  
Earth Rotation ◽  
Polar Motion ◽  
Satellite Laser Ranging ◽  
Laser Ranging ◽  
International Earth Rotation Service ◽  
Global Tracking ◽  
International Earth Rotation ◽  
Earth Rotation Parameters ◽  
Rotation Parameters

AbstractThe Satellite Laser Ranging (SLR) technique has been used to determine Earth Rotation Parameters (ERP) for over twenty years. Most of results contributed to the International Earth Rotation Service (IERS) are based on analysis of observations of Lageos 1 & 2 satellites collected by the global tracking network of about 40 stations. Now five analysis centers submit operational (with 2–15 days delay) solutions and about ten analysis centers contribute yearly final (up to 23 years) ERP series. Some statistics related to SLR observations and analysis are presented and analyzed. Possible problems in SLR observations and analysis and ways of its solution are discussed.

scholarly journals Astrometric Latitude and Time Observational Database at Shanghai Observatory

1993 ◽  
Vol 156 ◽  
pp. 433-433
Author(s):  
Zheng-Xin Li ◽  
You-Fen Chen ◽  
Chang-Xia Qian
Keyword(s):  
Observational Data ◽  
Earth Rotation ◽  
International Earth Rotation Service ◽  
The Past ◽  
International Earth Rotation ◽  
Earth Rotation Parameters ◽  
The World ◽  
Time Determination ◽  
Rotation Parameters ◽  
The Moment

After the closing of Bureau International de L'Heure (BIH) and the establishment of International Earth Rotation Service (IERS) at the end of 1987. Shanghai Observatory has been the institute where the astrometric latitude and time observational data are collected and treated. During the past four years, about 75,293 measurements in latitude or time determination have been obtained by the 64 optical astrometric instruments over the world from which the five-day Earth Rotation Parameters of the 1988–1990 period have still been reduced. Twelve Quarterly Report on the optical ERP have been distributed. Since the beginning of 1991 the regular reduction of the ERP has been stopped but the collecting of the observational data is still going on in Shanghai Observatory in order to meet the requirements of the scientists who are still interested on the studies concerned with these observations. There are still 42 optical astrometric instruments taking part into the regular observations at the moment.

scholarly journals The Celestial System and Frame of IERS

1991 ◽  
Vol 127 ◽  
pp. 198-201 ◽  
Author(s):  
E.F. Arias ◽  
M. Feissel
Keyword(s):  
Dynamical Systems ◽  
Physical Properties ◽  
Internal Consistency ◽  
Earth Rotation ◽  
International Earth Rotation Service ◽  
International Earth Rotation

AbstractThe celestial system maintained by the International Earth Rotation Service is described in terms of physical properties of the fiducial objects, internal consistency of the frame, and agreement with the FK5 and dynamical systems.

scholarly journals The Present Status of Preparing the New Reduction of the Past Astrometric Observations to Obtain the Earth Orientation Parameters in the Hipparcos Reference System

1993 ◽  
Vol 156 ◽  
pp. 95-100
Author(s):  
J. Vondrák ◽  
C. Ron
Keyword(s):  
Reference Frame ◽  
Present Status ◽  
Earth Rotation ◽  
Main Idea ◽  
Earth Tides ◽  
Star Catalog ◽  
Earth Rotation Parameters ◽  
Set Up ◽  
The Individual ◽  
Celestial Reference Frame

The IAU Working group on Earth rotation in the Hipparcos reference frame, set up by IAU Commission 19 in 1988, is presently preparing the algorithms and collecting the data obtained by optical astrometry since the beginning of the century. The main idea is to use the observations of individual stars rather than group results, all recalculated in the unique system of astronomical constants and algorithms. The final solution will be referred to the celestial reference frame realized by the Hipparcos star catalog presently under preparation. All known geophysical influences (as e.g. solid and oceanic Earth tides or plate tectonic movements) will be included into the model. In addition to traditional Earth rotation parameters (polar motion, universal time), also the pole offset components in the celestial reference frame will be solved for, as well as other relevant parameters (systematic seasonal deviations of the individual stations, instrumental constants etc.). The present status of the solution and the time evolution of its expected accuracy are described.

scholarly journals The role of Japan in the new international Earth rotation service (expected contribution of the planned Japanese VLBI system VERA)

1988 ◽  
Vol 128 ◽  
pp. 439-444
Author(s):  
K. Yokoyama ◽  
S. Manabe
Keyword(s):  
Simulation Study ◽  
Earth Rotation ◽  
International Earth Rotation Service ◽  
The Earth ◽  
International Earth Rotation ◽  
Precision And Accuracy ◽  
Rotation Study

The outline of the planned Japanese VLBI system for the Earth rotation study and astrometry (VERA) is described. As a result of simulation study, it is concluded that precision and accuracy of the VLBI estimates of astronomical and geophysical parameters are remarkably improved when VERA participates in the present IRIS network.

scholarly journals The Celestial System of the International Earth Rotation Service

1990 ◽  
Vol 141 ◽  
pp. 119-128
Author(s):  
E.F. Arias ◽  
M. Feissel
Keyword(s):  
Earth Rotation ◽  
Geodetic Survey ◽  
Radio Sources ◽  
National Geodetic Survey ◽  
International Earth Rotation Service ◽  
International Earth Rotation ◽  
Goddard Space Flight Center ◽  
Celestial Pole ◽  
Conventional Models ◽  
Celestial Reference Frame

The celestial system of the International Earth Rotation Service (IERS) is materialized by the J2000.0 positions of more than 250 extragalactic compact radio sources observed by VLBI. The source coordinates are evaluated from the combination of individual celestial frames obtained by the Goddard Space Flight Center, the Jet Propulsion Laboratory and the U.S. National Geodetic Survey.The combination model and the maintenance algorithm are described. To free the IERS celestial frame from inconsistencies due to the inaccuracy of the IAU conventional models for precession and nutation, it is implemented on individual frames which have been obtained in parallel to the adjustment of corrections to the direction of the celestial pole.The IERS celestial reference frame is consistent with FK5 at a few milliarcsecond level. To be made denser and more accessible for astronomical uses, it will be related to the HIPPARCOS stellar frame.

scholarly journals The Background to the Merit/Cotes Recommendations on the Terrestrial and Celestial Reference Systems

1986 ◽  
Vol 7 ◽  
pp. 81-84
Author(s):  
G A Wilkins
Keyword(s):  
International Collaboration ◽  
Earth Rotation ◽  
Reference Frames ◽  
Radio Sources ◽  
Reference Systems ◽  
International Earth Rotation Service ◽  
Earth Rotation Parameters ◽  
Working Groups ◽  
Rotation Parameters ◽  
Better Than

AbstractThe MERIT programme of international collaboration to monitor earth-rotation and to intercompare the techniques of observation and analysis has fostered the development of the use of space techniques. Earth-rotation parameters are now determined regularly with a precision that is better than 1 milliarcsecond () and the relative positions of the observing stations are determined to better than 1 decimetre (0.1 m). It is therefore necessary that the terrestrial and celestial reference frames be defined more precisely. The MERIT and COTES Working Groups have proposed that new conventional terrestrial and celestial reference systems be established and that the maintenance of these systems be the responsibility of a new International Earth Rotation Service. The new reference frames are to be based on the adoption of positions and motions of designated stations and extragalactic radio sources. Appropriate models and parameters will be associated with these frames to form reference systems so that observations can be used to determine the rotation of the terrestrial frame with respect to the celestial frame.

scholarly journals CQSSP: A New Technique for Establishing the Tie Between the Stellar and Quasar Celestial Reference Frames

1991 ◽  
Vol 127 ◽  
pp. 341-347
Author(s):  
T. Schildknecht ◽  
I. Bauersima ◽  
U. Hugentobler ◽  
A. Verdun ◽  
G. Beutler
Keyword(s):  
Reference Frame ◽  
Earth Rotation ◽  
Reference Frames ◽  
Terrestrial Reference Frame ◽  
Optical Observations ◽  
Artificial Satellites ◽  
Satellite Orbits ◽  
Earth Rotation Parameters ◽  
A New Technique ◽  
Celestial Reference Frame

AbstractUsing artificial satellites as transfer objects the project “Coupled Quasar-Satellite-Star Positioning” represents an independent method for linking quasar and stellar reference frames. Optical observations of close approaches between reference stars and satellites yield satellite positions in the stellar reference frame. On the other hand high precision satellite orbits in the International Earth Rotation Service (IERS) terrestrial reference frame are obtained from laser or radiometric observations. Using IERS earth rotation parameters and adopted transformation models the satellite and eventually the star positions can be expressed in the IERS quasar celestial reference frame. In this paper we describe the CQSSP project and assess its capability for providing an accurate tie between tho two metioned celestial reference frames.

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