Time and the Earth¿s Rotation

IAU Symposium No. 82, "Time and the Earth's Rotation", met to discuss modern research in the field of the rotation of the Earth with particu­ lar emphasis on the role of new observational techniques in this work. The use of these techniques has prompted a new look at the definitions of the traditional reference systems and the concepts of the rotation of the Earth around its center of mass. Specific topics discussed were time, polar motion, reference systems, conventional radio interferometry, very'long baseline interferometry (VLBI), Doppler satellite methods, satellite laser ranging, lunar laser ranging, and geophysical research concerning the Earth's rotation. Improvement in the accuracy of the observations is a key to possible solutions of the many unsolved problems remaining in this field. It appears that such improvement, using both classical and new techniques, is forthcoming in the near future. This will surely contribute to a better understanding of some of the long-standing questions concerning the rotation of the Earth around its center of mass and lead to an improved knowledge of the rotating, deformable Earth. This volume contains the papers presented at IAU Symposium No. 82 as well as the discussions provoked by these papers. It is hoped that it captures the principal points of the meeting and that it will contribute not only to a better understanding of existing problems, but also to future research in time and the Earth's rotation.

Introduction: The Future of the Researches About the Earth’s Rotation.- I. Time.- Basic Problems in the Kinematics of the Rotation of the Earth (Invited Paper).- A New State Time and Frequency Standard of the USSR.- A New Method of Universal Time Computation Used in the State Time and Frequency Service of the USSR.- On the Determination of UT1 by the BIH and the U.S.S.R, Time Service.- Etude d’Observations Effectuées à l’Astrolabe de Paris et Comparaison avec d’Autres Resultats Concernant les Termes Principaux de la Nutation.- A New System of the U.S.S.R, Standard Time for 1955-1974 and its Application in the Study of the Earth’s Rotation.- An Analysis of the Rotational Acceleration of the Earth (Abstract).- New Determination of the “Decade” Fluctuations in the Rotation of the Earth, 1860–1978 (Abstract).- On the Long-Period Variations in the Rate of the Earth’s Rotation (Abstract).- Main Results of Studying the Nature of the Irregularity of the Earth’s Rotation.- Some Advantages and Disadvantages of a Photographic Zenith Tube (abstract).- Tidal Perturbations in Astronomical Observations.- Polar Motion and Earth Rotation Monitoring in Canada.- Polar Coordinates and UT1-UTC from PZT Observations.- (?-2L) Terms as Obtained from PZT Observations.- Etude Succinte du Catalogue Fondamental FK4 à Partir des Observations Faites à 1’Astrolabe.- II. Polar Motion.- On the Coordinate Systems Used in the Study of Polar Motion (Invited Paper).- Derivation of Pole Coordinates in a Uniform System from the Past ILS Data.- On the Computation of Accurate Earth Rotation by the Classical Astronomical Method.- On the Relative Motion of the Earth’s Axis of Figure and the Pole of Rotation.- Secular Variation of Tashkent Astronomical Latitude (Abstract).- Coordinates of the Pole for the Period 1968-1974 Computed in the System of 10 Stations with Small Variations of Mean Latitudes.- Amelioration des Calculs de Reduction des Observations à l’ Astrolabe. Application à la Determination des Termes de 18.6 et 9.3 Ans de la Nutation.- Time and Latitude Programs at the National Observatory of Brazil.- Preliminary Analysis of Astrolabe Observations at Merate Observatory During the Period 1970–1977 (Abstract).- The Longitude Difference Merate- Milano Derived from Danjon Astrolabe Observations by Means of a One-Step Adjustment Using an Extended Model.- Velocity of the Motion of the Terrestrial Pole.- III. Reference Systems.- The Reference Systems (Invited Paper).- The Ephemeris Reference Frame for Astrometry.- Nutation in Space and Diurnal Nutation in the Case of an Elastic Earth.- Concept for Reference Frames in Geodesy and Geodynamics: The Reference Directions (Abstract).- IV. Radio Interferometry.- An Introduction to Radio Interferometric Techniques.- The Application of Radio Interferometric Techniques to the Determination of Earth Rotation (Invited Paper).- An Improved Polar Motion and Earth Rotation Monitoring Service Using Radio Interferometry.- Determination of UT1 and Polar Motion by the Deep Space Network Using Very Long Baseline Interferometry.- The NAVOBSY/NRL Program for the Determination of Earth Rotation and Polar Motion.- Recent Results of Radio Interferometric Determinations of a Transcontinental Baseline, Polar Motion, and Earth Rotation.- Precision Estimates of Universal Time from Radio-Interferometrie Observations.- V. Satellite Laser Ranging.- Determination of Polar Motion and Earth Rotation from Laser Tracking of Satellites (Invited Paper).- Polar Motion from Laser Range Measurements of GEOS-3.- Low Cost Lageos Ranging System (Abstract).- VI. Lunar Laser Ranging.- On the Effective Use of Lunar Ranging for the Determination of the Earth’s Rotation (Invited Paper).- Is Lunar Ranging a Viable Component in a Next-Generat ion Earth Rotation Service?.- Preliminary UTO Results from EROLD Data.- VII. Doppler Satellite Methods.- Polar Motion through 1977 from Doppler Satellite Observations (Invited Paper).- Irregularities of the Polar Motion.- Reasons and Possibilities for an Extended Use of the Transit System.- Very First Results of the MEDOC Experiment.- VIII. Geophysics.- The Geophysical Interpretation of Changes in the Length of the Day and Polar Motion.- Estimation of the Parameters of the Earth’s Polar Motion.- Rotational Velocity of an Earth Model with a Liquid Core (Abstract).- On Investigations of the Tidal Waves Mf and Mm (Abstract).- Oceanic Tidal Friction: Principles and New Results.- The Stability of Continental Blocks in Seismically Active Regions (Abstract).- General Discussion.- Resolutions.