The IAU Resolutions on Astronomical Reference Systems, Time Scales, and Earth Rotation Models (Draft 4)

2005 ◽  
Author(s):  
George H. Kaplan
Keyword(s):  
Time Scales ◽  
Earth Rotation ◽  
Reference Systems

scholarly journals Relativistic aspects of rotational motion of celestial bodies

2009 ◽  
Vol 5 (S261) ◽  
pp. 112-123 ◽  
Author(s):  
S. A. Klioner ◽  
E. Gerlach ◽  
M. H. Soffel
Keyword(s):  
High Precision ◽  
Rotational Motion ◽  
Earth Rotation ◽  
Theoretical Framework ◽  
Reference Systems ◽  
The Moon ◽  
Newtonian Theory ◽  
Recent Developments ◽  
Celestial Bodies ◽  
Near Future

AbstractRelativistic modelling of rotational motion of extended bodies represents one of the most complicated problems of Applied Relativity. The relativistic reference systems of IAU (2000) give a suitable theoretical framework for such a modelling. Recent developments in the post-Newtonian theory of Earth rotation in the limit of rigidly rotating multipoles are reported below. All components of the theory are summarized and the results are demonstrated. The experience with the relativistic Earth rotation theory can be directly applied to model the rotational motion of other celestial bodies. The high-precision theories of rotation of the Moon, Mars and Mercury can be expected to be of interest in the near future.

scholarly journals Atmospheric Effects on Earth Rotation and Polar Motion

1988 ◽  
Vol 129 ◽  
pp. 401-410
Author(s):  
David A. Salstein
Keyword(s):  
Time Scales ◽  
Earth Rotation ◽  
Polar Motion ◽  
Atmospheric Effects ◽  
Length Of Day ◽  
Wind Fields ◽  
Wind Variability ◽  
Body Tides ◽  
Wind Distribution

The variability in the earth's rotation rate not due to known solid body tides is dominated on time scales of about four years and less by variations in global atmospheric angular momentum (M), as derived from the zonal wind distribution. Among features seen in the length of day (Δl.o.d.) record produced by atmospheric forcing are the strong seasonal cycle, quasi-periodic fluctuations around 40–50 days, and an interannual signal forced by a strong Pacific warming event, known as the El Niño. Momentum variations associated with these time scales arise in different latitudinal regions. Furthermore, winds in the stratosphere make a particularly important contribution to seasonal variability.Other related topics discussed here are (i) comparisons of the M series from wind fields produced at different weather centers, (ii) the torques that dynamically link the atmosphere and earth, and (iii) longer-term non-atmospheric effects that can be seen upon removal of the atmospheric signal. An interesting application for climatological purposes is the use of historical earth rotation series as a proxy for atmospheric wind variability prior to the era of upper-air data. Lastly, results pertaining to the role of atmospheric pressure systems in exciting rapid polar motion are presented.

scholarly journals Relativity in the IERS Conventions

2009 ◽  
Vol 5 (S261) ◽  
pp. 16-21
Author(s):  
Gérard Petit
Keyword(s):  
Earth Rotation ◽  
Reference Systems ◽  
International Earth Rotation ◽  
Working Groups ◽  
General Relativistic ◽  
Definition Of

AbstractIn the last years, a fully general relativistic definition of reference systems and of their application to astronomy and geodesy has been passed into Resolutions of the scientific unions, following work of several working groups and of the community at large. In this community, the role of the International Earth Rotation and Reference systems Service (IERS) is to generate the terrestrial and celestial reference systems and the transformation between them, and the IERS Conventions provide the set of models and procedures used in the generation of IERS products. It is therefore essential that the IAU framework for relativity is introduced in the IERS Conventions, and that this is done consistently and completely throughout the document. The paper reviews relativistic aspects in the IERS Conventions and presents recent and on-going work aiming at providing a complete and consistent presentation for a new reference edition of the IERS Conventions, expected to appear in the next year.

scholarly journals INFLUENCE OF ROTARY POST-EFFECT ON DISCHARGE IN THE CRUSTAL LAYER

2021 ◽  
Vol 26 (1) ◽  
pp. 16-24
Author(s):  
Sergei V. Dolin ◽  
◽  
Vadim F. Kanushin ◽  
Keyword(s):  
Time Scales ◽  
Earth Rotation ◽  
Annual Number ◽  
Angular Rotation ◽  
Crustal Layer ◽  
Analytical Analysis ◽  
Partial Derivatives ◽  
Rotation Rates ◽  
The Earth ◽  
Derivatives Of

This work represents experiments which have been performed in an attempt to establish a correla-tion between the constantly changing rotational regime of the planet and the discharge in the crustal layer. From the displacement of the TAI, UTC, and UT1 time scales taken from the site of the Interna-tional Earth Rotation Service (IERS), the average annual and monthly angular rotation rates were cal-culated for the period from 1962 to 2018, and a catalog of earthquakes with 1962 to 2018. The com-piled algorithm and the written program found partial derivatives of the total deforming potential and the distribution of annual number of earthquakes over the Earth's surface per one square kilometer. The article presents the results of analytical analysis and calculations for further investigation of the rotational regime of the Earth and other planets.

scholarly journals The Origin of Celestial Coordinates

1990 ◽  
Vol 141 ◽  
pp. 51-59
Author(s):  
C. A. Murray
Keyword(s):  
Earth Rotation ◽  
Zero Point ◽  
Rate Of Change ◽  
Reference Systems ◽  
The Earth ◽  
Private Correspondence ◽  
Rotation Of The Earth ◽  
Right Ascension

In 1978, Guinot proposed that, for studies of Earth rotation, the zero point of the apparent “right ascension” coordinate on the true equator should be so chosen that the rate of change of its hour angle is exactly proportional to the inertial rate of rotation of the Earth. It has been subsequently suggested that this concept of the “non-rotating origin” supersede the equinox quite generally as the origin of celestial coordinates. Since this proposal was first put forward, there has been much discussion, and some criticism, from Aoki and his colleagues, both published and in private correspondence. Some of the arguments for and against Guinot's proposal are discussed, as a contribution to the wider debate on reference systems now being carried out under the auspices of the IAU.

scholarly journals Report of the IAU WGAS Sub-group on Issues on Time

1995 ◽  
Vol 10 ◽  
pp. 193-196
Author(s):  
P.K. Seidelmann
Keyword(s):  
Time Scales ◽  
Working Group ◽  
Reference Systems ◽  
Coordinate Time ◽  
Dynamical Time ◽  
Different Time Scales

Included in the nine adopted recommendations of the IAU Working Group on Reference Systems (Hughes, et. al., in 1991), were recommendations for the introduction of Geocentric Coordinate Time (TCG) and Barycentric CoordinateTime (TCB), the renaming of the Terrestrial Dynamical Time (TDT) as Terrestrial Time (TT), and the approval to continue the use of Barycentric Dynamical Time (TDB) when that is desirable. The relationships between these different time scales and the reason for their introduction was given by Seidelmann and Fukushima (1992). Since it was recognized that there were some unresolved issues as a result of these recommendations, a subcommittee of the Working Group on Astronomical Standards was established for Issues on Time.

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 Presentation of WGRS Recommendations I to V

1992 ◽  
Vol 9 ◽  
pp. 116-119
Author(s):  
B. Guinot
Keyword(s):  
Time Scales ◽  
Space Time ◽  
Point Of View ◽  
Reference Systems ◽  
Global Approach ◽  
Dynamical Time ◽  
Time Standards ◽  
Primary Mission ◽  
Relativistic Framework ◽  
Atomic Time

I start by general remarks on the background of the recommendations on space-time references which are submitted to you.The need to consider time scales in a relativistic framework appeared more than 20 years age following the progress of atomic time standards. After long discussions, this led the IAU to define, In 1976, time scales which were designated, In 1979, as Terrestrial Dynamical Time (TDT) and Barycentric Dynamical Time (TDB). But soon afterwards difficulties in the interpretation of the definitions of TDT and TDB arose. It appeared that the source of these difficulties was the lack of a global approach to space-time reference systems. This point of view, first voiced by J. Lieske, gained acceptance. At the very beginning of the work of the WGRS Sub-Groups on Frames and Origins (SGFO) and on Time (SGT), It became clear the the primary mission of the SGFO and SGT was to jointly prepare general recommendations on space-time references on which they could base their specific recommendations.

scholarly journals Ephemeris Astronomy Definitions and Constants in General Relativity

1997 ◽  
Vol 165 ◽  
pp. 439-446
Author(s):  
Victor A. Brumberg
Keyword(s):  
General Relativity ◽  
Time Scales ◽  
Absolute Space ◽  
Newtonian Mechanics ◽  
Reference Systems ◽  
Absolute Time ◽  
Astronomical Constants

AbstractCurrently employed definitions of ephemeris astronomy and the system of astronomical constants are based on Newtonian mechanics with its absolute time and absolute space. To avoid any relativistic ambiguities in applying new IAU (1991) resolutions on reference systems (RS) and time scales one should specify the astronomical constructions and definitions of constants to make them consistent with general relativity (GRT). Such an approach is developed with the aid of the existing relativisting hierarchy of relativistic reference systems and time scales.

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