Dennis McCarthy

Dennis McCarthy
Dennis McCarthy

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203
Publications
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2,293
Citations
Citations since 2017
9 Research Items
454 Citations
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
Introduction
Skills and Expertise

Publications

Publications (203)
Article
Full-text available
IAU Commission 19 began in 1919 with the birth of the IAU at the Brussels Conference, where Standing Committee 19 on Latitude Variations was established as one of 32 standing committees. At the first IAU General Assembly in 1922, Standing Committee 19 became Commission 19 “Variation of Latitude”. In the beginning, the main topic of the Commission w...
Book
Cambridge Core - Time: From Earth Rotation to Atomic Physics - by Dennis D. McCarthy
Article
Full-text available
This report continues the practice where the IAU Working Group on Cartographic Coordinates and Rotational Elements revises recommendations regarding those topics for the planets, satellites, minor planets, and comets approximately every 3 years. The Working Group has now become a “functional working group” of the IAU, and its membership is open to...
Conference Paper
Full-text available
We present our ongoing investigation of the use of U.S-produced atmospheric and oceanic angular momentum (AAM and OAM) estimates to improve the determination of near real-time Earth rotation and polar motion parameters and their short-term predictions. Previous investigations provided evidence that the use of AAM and OAM data sets could improve sho...
Data
Very Long Baseline Interferometry (VLBI) is a primary space-geodetic technique for determining precise coordinates on the Earth, for monitoring the variable Earth rotation and orientation with highest precision, and for deriving many other parameters of the Earth system. The International VLBI Service for Geodesy and Astrometry (IVS, http://ivscc.g...
Article
The astronomical unit (au) is a unit of length approximating the Sun - Earth distance that is used mainly to express the scale of the solar system. Its current definition is based on the value of the Gaussian gravitational constant, k. This conveniently provided accurate relative distances (expressed in astronomical units) when absolute distances c...
Article
To keep the calendar year synchronized with the astronomical year, intercalary days are inserted following a commonly adopted convention that defines the Gregorian Calendar. Similarly, to keep the day composed of 86, 400 Système Inter national (SI) seconds synchronized with the day defined by the Earth’s rotation, intercalary seconds are occasional...
Article
Astronomy has provided a means to mark the passage of time throughout history. One of the repeating phenomena that makes this possible is the Earth's rotation. The basic variability in its rotational speed, however, makes astronomical techniques unsuitable for timekeeping with the precision required for modern applications. Physical metrology from...
Article
Full-text available
There were four 1.5-hour sessions of Division I business meetings during the XXVIIth IAU General Assembly. The first three were devoted to the reports of Commissions, Working Groups and services associated with the Division, discussion about plans for the next triennium and future structure of the Division. Scientific presentations on the future sp...
Chapter
Newtonian Reference SystemsSpecial RelativityLorentz TransformationsCoordinate and Proper TimeMinkowski DiagramsTime in Special RelativityGeneral RelativityIAU ResolutionsTime ScalesRelativistic Effects in Time TransferReferences
Chapter
Historical Transfer TechniquesTime and Frequency Dissemination ModelingTime and Frequency Dissemination SystemsReferences
Chapter
Time Enables the InfrastructurePositioning and Navigation ServicesCommunicationsPower GridBanking and FinanceEmergency ServicesWater FlowSummaryReference
Chapter
Time and International ActivitiesTreaty of the MeterScientific UnionsService OrganizationsReferences
Chapter
Replacing Ephemeris TimeTerrestrial Dynamical Time (TDT) and Barycentric Dynamical Time (TDB)Problems with TDT and TDBNew Reference SystemNew Time ScalesΔT and Ephemeris Time RevisedRelationships Among Coordinate Time ScalesReferences
Chapter
Future Needs for TimeModeling the Earth's RotationClocks of the FutureFuture Time ScalesFuture Time Distribution
Chapter
Universal Time Before 1972Coordinated Universal Time After 1972Leap SecondsUT1UTC WorldwideTime DistributionThe Future of UTC – Leap Seconds or Not?References
Chapter
Apparent Solar TimeMean Solar TimeEquation of TimeSidereal TimeWashington Conference of 1884Newcomb's Theory of the SunUniversal TimeCoordinated Universal Time (UTC)Greenwich Mean Time (GMT)Tropical YearBesselian YearReference SystemTime ZonesDaylight Saving TimeReferences
Chapter
Ephemerides and TimeBefore Kepler and NewtonKepler and NewtonTables, General Theories, and EphemeridesLunar TheoriesThe Advent of ComputersNumerical IntegrationsObservational DataDynamical Reference FrameTime ArgumentsAstronomical ConstantsArtificial Satellite TheoriesTheory of RelativityReferences
Chapter
Pre 19th CenturySecular VariationIrregular Variations in the Earth's RotationEarly Explanations for the Variable RotationCurrent Understanding of the Earth's Variable RotationConsequencesReferences
Chapter
Earth OrientationVariations in the Earth's OrientationTransforming Between Reference FramesDetermination of Earth OrientationEarth Orientation DataReferences
Chapter
The Solar SystemPursuit of UniformityPursuit of AccuracyTime and PhenomenaTime and DistanceSpace Mission TimesProper Times at PlanetsPulsars – An Independent Source of Time?References
Chapter
The Historical SecondThe Ephemeris SecondThe SI SecondAdopting the SI SecondReferences
Chapter
Beyond Quartz-Crystal OscillatorsPhysics of Atomic ClocksGeneral Structure of Atomic ClocksDevelopment of Atomic ClocksStored Ion ClocksCharacterizing Atomic ClocksReferences
Chapter
Terrestrial to Celestial Reference SystemsDetermination of Earth Orientation ParametersEarth Orientation DataReferences
Chapter
IntroductionKeeping Time in AntiquityThe First Mechanical ClocksPendulum ClocksQuartz Crystal ClocksClock PerformanceReferences
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Constructing an Atomic Time ScaleHistory of TAIFormation of TAIStability of TAIDistribution of TAIRelationship of TAI to Terrestrial TimeReferences
Chapter
In the BeginningCharacterizing TimeCalendarsAstronomical ObservationsTimekeepingTime EpochsTime TransferRotation of the EarthBeginning the Twentieth CenturyReferences
Article
Full-text available
Division I provides a focus for astronomers studying a wide range of problems related to fundamental physical phenomena such as time, the inertial reference frame, positions and proper motions of celestial objects and precise dynamical computation of the motions of bodies in stellar or planetary systems in the Universe.
Article
Recent developments in clock technology have made it possible to provide time and frequency with unprecedented precision in the laboratory. The challenge of comparing these devices at a distance remains, however. A critical component in transferring time and frequency is the consideration of the relativistic aspects of time comparisons. For example...
Article
Filling the need for a book that conveys the current technology as well as the underlying history and physical background, this book tells physicists and engineers how to measure time to the precision required for modern-day use. The authors draw on their longstanding research experience with timekeeping and high-precision measurement to cover the...
Article
Full-text available
Aleksander Brzezinski, P-C19 (Poland), Joseph A. Burns, P-C7 (USA), Pascale Defraigne, P-C31 (Belgium), Dafydd Wyn Evans, VP-C8 (UK) Toshio Fukushima, P-C4, PP (Japan), George H. Kaplan, VP-C4 (USA), Sergei A. Klioner, P-C52 (Germany), Zoran Knezevic, VP-C7 (Serbia) Irina I. Kumkova, P-C8 (Russia), Chopo Ma, VP-C19 (USA), Richard N. Manchester, VP-...
Article
Full-text available
International Atomic Time (TAI) is the internationally recognized timescale based on the second of the Système International d'Unités produced by the Bureau International des Poids et Mesures using data from timing laboratories around the world. TAI is an atomic timescale without steps. Coordinated Universal Time, the basis of civil time, is derive...
Article
Full-text available
A Division 1 Working Group on “Nomenclature for Fundamental Astronomy” (NFA) was formed at the 25th IAU GA in 2003 in order to provide proposals for the new nomenclature associated with the implementation of the IAU 2000 resolutions on reference systems. This WG is also intended to make related educational efforts for addressing the issue to the la...
Article
Observations of the length of day, corrected for the effects of variations in the angular momentum due to changes in wind velocity and atmospheric pressure, ocean-tide heights and currents, and solid-Earth zonal tides, were analysed. the (1992) IERS Standards model for the effects of zonal tides on the Earth's rotation, which includes ocean-tidal e...
Article
Full-text available
The definition of UTC was implemented in 1972, principally to accommodate celestial navigation and follows recommendation 460 of the International Radio Consultative Committee (CCIR) in 1970. Since 1972 the use of electronic means to navigate has overtaken celestial navigation. This fact along with increasing public dissatisfaction with the possibl...
Article
The typical GPS receiver solves the position, velocity and timing (PVT) problem, using pseudo-range measurements, relative to an Earth centered fixed (ECF) coordinate reference frame. By design, GPS satellites broadcast their ephemeris using continuous functions of quasi-Keplerian orbital element in ECF coordinates. However, for spacecraft applicat...
Article
The International Earth rotation and Reference system Service (IERS) provides observational determinations of the celestial pole offsets that describe quantitatively the differ-ence between the observed direction of the Celestial Intermediate Pole in the celestial reference frame and the direction predicted by the conventional precession-nutation m...
Article
Full-text available
Stochastic prediction techniques including autocovariance, autoregres-sive, autoregressive moving average, and neural networks were applied to the UT1-UTC and Length of Day (LOD) International Earth Rotation and Reference Systems Service (IERS) EOPC04 time series to evaluate the capabilities of each method. All known ef-fects such as leap seconds a...
Article
Full-text available
The consistency of the reference frames provided by the IERS and its different centers relies on the set of conventional models and procedures that are used to realize them. These conventional models and procedures are mostly the product of the IERS Conventions Center, provided jointly by the Bureau International des Poids et Mesures (BIPM) and the...
Article
The IAU Joint Discussion 16 (JD16) was held in conjunction with the XXVth General Assembly in July, 2003. Papers related to the maintenance of the International Celestial Reference System were presented in the one-day session, and these were followed by discussion that pointed out the need for standard nomenclature. This issue was addressed by the...
Article
Full-text available
The International Celestial Reference Frame (ICRF) is currently a radio reference frame accessed through VLBI that is refined with technique-dependent improvements described in this Joint Discussion. An important component of the International Celestial Reference System (ICRS) that is the basis for this frame is the set of conventional models...
Article
Practical measurement of the passage of time requires the notion of a repeating phenomenon. The Earth's rotation has traditionally fulfilled this requirement. To cope with the impracticality of making precise measures of the Sun's hour angle or altitude, particularly in uncooperative weather conditions, various devices have been employed, but all h...
Conference Paper
GPS Time, the time scale internal to the Global Positioning System, is a uniform scale of time without leap seconds having an initial epoch of midnight, January 5/6, 1980 UTC. Galileo proposes to use a realization of TAI, another scale without leap seconds, as its internal time scale. However, TAI is ahead of GPS Time by 19 seconds, a constant valu...
Article
Resolutions adopted by the International Astronomical Union (IAU) in 2000 recommend significant improvements in the definition of the International Celestial Reference System and the procedures to be used in its realization. These recommendations correspond with the unprecedented observational accuracy that is now achievable in accessing the refere...
Article
This document is intended to define the standard reference systems realized by the International Earth Rotation Service (IERS) and the models and procedures used for this purpose. It is a continuation of the series of documents begun with the Project MERIT Standards (Melbourne et al., 1983) and continued with the IERS Standards (McCarthy, 1989; McC...
Article
Full-text available
This paper provides expressions to be used to implement the new definition of UT1 corresponding to the IAU 2000 resolutions either in the new (CEO-based) or classical (equinox-based) transformations between the International Terrestrial Reference System (ITRS) and the Geocentric Celestial Reference System (GCRS). The new expression for Greenwich Si...
Article
The expressions for the X and Y coordinates of the CIP in the GCRS and the quantity s(t)+XY/2 are based on the IAU2000A precession-nutation model. They are in the form : polynomial part + non-polynomial part In the non-polynomial part, ARG being for various combination of the fundamental arguments of the nutation theory) The expressions for the fun...
Article
Full-text available
This paper reviews the theoretical motivation for the leap second in the context of the historical evolution of time measurement. The periodic insertion of a leap second step into the scale of Coordinated Universal Time (UTC) necessitates frequent changes in complex timekeeping systems and is currently the subject of discussion in working groups of...
Article
Precise astrometric observations show that significant systematic differences of the order of 10 milliarcseconds (mas) exist between the observed position of the celestial pole in the International Celestial Reference Frame (ICRF) and the position determined using the International Astronomical Union (IAU) 1976 Precession (Lieske et al., 1977) and...
Article
Full-text available
In this paper, four different methods for the prediction of x, y pole coordinates are investigated. We examined the accuracies of autocovariance (AC), least-squares extrap-olation (LS), a least-squares extrapolation and autoregressive combination (LS+AR), and a least-squares extrapolation and neural networks combination (LS+NN) in predicting pole p...
Article
In the future improvement of the IERS combination solutions it will be necessary to address the role of the adopted conventions on the precision and accuracy of the product. It is suggested that the first step be the establishment of clear conventions within each technique followed by a joint effort of the Conventions Center and the Analysis Coordi...
Article
Full-text available
Analyses of residuals between VLBI observations and combinations of nutation series show that the MHB 2000 nonrigid-Earth nutation model applied to the REN 2000 rigid-Earth model results in the best fit, and that amplitudes of any possible periodic terms remaining in the observed corrections to the MHB2000 theory could be expected to be less than 0...
Article
Past endeavors in the field of Earth orientation have provided both service to astronomical users of the data and insight into the physical processes of the planet Earth. Since the study of Earth orientation has required a wide geographic distribution of astronomical observing sites, it has been an area of research that has depended heavily on inte...
Article
This topic addresses the issue of the compatibility of observations made in the past with observations made using the new system. It is not likely that there would any requirement to adjust past observations to put them into a system that complies with the newly adopted IAU Recommendations. However, it may be important to look at the specifics of e...
Article
Full-text available
The polar motion prediction is computed as a least-squares extrapolation of the polar motion data. The least-squares model consists of a Chandler circle with constant or variable amplitude, annual and semiannual ellipses, and a bias. The model with constant amplitude of the Chandler oscillation is fit to the last three years of polar motion data an...
Article
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Article
With the beginning of the 21st Century, the timing community finds itself again facing a decades-old problem of how to synchronize a uniform time scale with time derived from the Earth's rotation. Atomic time is the basis for most everyday timing applications, However, time astronomically determined from the Earth's rotation is essential for other...
Article
The tables contain the parameters of the development as functions of time t (expressed in centuries since J2000.0) of the Celestial Pole Coordinates X and Y, expressed in arcseconds, has the following form: X=-0.017130 + 2004.193319t - 0.4271605t2 - 0.1986210t3 -0.0000461t4 + 0.0000058t5 +{Sum on i}[(as,0)isin(ARGUMENT)+(ac,0)icos(ARGUMENT)] +{Sum...
Article
Full-text available
The current definition of Coordinated Universal Time (UTC) is related to the unpredictable, variable rotation rate of the Earth. This is accomplished by irregular insertions of leap seconds, creating unpredictable discontinuities in UTC. With the increasing importance of a continuous, uniform time scale for users, it is appropriate to re-examine th...
Article
Full-text available
The adoption of the International Celestial Reference System ICRS, and of the corresponding Frame, ICRF, by the 23rd General Assembly of the International Astronomical Union, calls for a redefinition of the departure point on the true equator. Several possibilities have been suggested. This paper considers the use of the non-rotating origin (Guinot...
Article
After one hundred years of intensive study, some aspects of polar motion remain poorly understood. This motion of the Earth’s axis of rotation with respect to its mantle and crust has been observed and studied since the creation of the International Latitude Service. Research has shown that the motion of the pole is quite complicated and distinguis...
Article
The last three years have been marked by changes, highlights and progress. Organizationally, commission 7 has joined Division I and plans proceed for commissions 8 and 24 to merge in 2000. They have had a common vice president during this triennium. Sadly, the Royal Greenwich Observatory was closed after over 200 years, but Her Majesty’s Nautical A...
Article
The triennial report of Commission 19 was composed from the contributions of its members. Space does not permit a listing of their names, but their contributions are sincerely appreciated. Unfortunately because of limited space it is also not possible to provide in this report the extensive list of publication of the Commission members. The list of...
Article
The authors present a prelminary description of the changes in the current procedures that will have to be performed in order to take into account the adoption of the ICRS as the new reference system and new nutation-precession series. A number of choices will have to be made: they are presented in this paper.
Article
This paper presents the reflections of the Working Group of which the tasks were to examine the non-rigid Earth nutation theory. To this aim, six different levels have been identified: Level 1 concerns the input model (giving profiles of the Earth's density and theological properties) for the calculation of the Earth's transfer function of Level 2;...
Article
 Autocovariance prediction has been applied to attempt to improve polar motion and UT1-UTC predictions. The predicted polar motion is the sum of the least-squares extrapolation model based on the Chandler circle, annual and semiannual ellipses, and a bias fit to the past 3 years of observations and the autocovariance prediction of these extrapolati...
Article
The solar potential perturbs light propagating in the solar system, providing the basis for tests of gravity through Very Long Baseline Interferometry (VLBI) observations of radio waves from extragalactic radio sources. Such observations determine the γ parameter of the Parameterized Post Newtonian (PPN) expansion of the spacetime metric, with the...
Chapter
The work of Commission 19 in the period 1993.5–1996.5 was concentrated both on observational and theoretical aspects of Earth rotation, namely on the mutual interaction of the rotating non-rigid Earth with other Solar System bodies as well as with the atmosphere and fluids (oceans, underground water). The activities were closely tied with the work...
Article
Historical sources of polar motion are analysed together with modern data in order to compile a set of coordinates of the mean pole in a reference system consistent with that of the International Earth Rotation Service. the trend and quasi-periodic motion of the pole are investigated, and we find that the rotational pole appears to be moving at the...
Chapter
Analyses of the orbits of the satellites of the Global Positioning System (GPS) by participants in the International GPS Service (IGS) (Mueller and Beutler, 1992) provide daily observations of high-accuracy polar motion. These data are used routinely by the International Earth Rotation Service (IERS) (see, for example, IERS Annual Report for 1993)....
Article
Variations of the orientation of the Earth in an inertial reference frame have been observed since Hipparchus. In addition to precession and nutation, astronomical observations have shown the nature of the variable rotational speed of the Earth and the motion of its rotational pole with respect to its surface. The historical observations are import...

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