The Astronomical Times, the Atomic Time and the Earth Rotation Angle

This chapter provides several operative definitions of time, together with the transformations among them, in order to complete the notions expounded by taking into account precession, nutation, aberration and the Earth rotation angle (ERA) and its variations. It introduces the notions and algorithm...

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Bibliographic Details
Published inFundamentals of Astronomy pp. 145 - 155
Main Authors Barbieri, Cesare, Bertini, Ivano
Format Book Chapter
LanguageEnglish
Published United Kingdom CRC Press 2021
Taylor & Francis Group
Edition2
Subjects
A-posteriori Analysis
Sidereal Year
UTC
TDT
Tropical Year
Sidereal Day
Diurnal Rotation
Anomalistic Year
Earth Moon Distance
Ephemeris Time
Hour Angle
Solar Day
Sidereal Time
Astronomical Almanac
Earth’s Rotation
GAST
IAU
International Terrestrial Reference
Annual Aberration
Julian
Lunar Orbit
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Summary:This chapter provides several operative definitions of time, together with the transformations among them, in order to complete the notions expounded by taking into account precession, nutation, aberration and the Earth rotation angle (ERA) and its variations. It introduces the notions and algorithms based on the ERA. The chapter details yearly revolution of the Earth provides a new timescale and of a new unit of time, namely, the year, which can be defined in several different ways. International atomic time (TAI) is certainly a very uniform time; nevertheless, according to general relativity, the frequency of any clock varies with the varying gravitational potential in which it is immersed. TAI is certainly a very uniform time; nevertheless, according to general relativity, the frequency of any clock varies with the varying gravitational potential in which it is immersed. The International Terrestrial Reference Frame is the realization of the International Terrestrial Reference System through a number of fiducial stations with well-known coordinates and velocities.
ISBN:9780367253202
9780367253493
0367253208
0367253496
DOI:10.1201/9780429287305-10