J/A+A/450/855 Methods for CIP and CIO localisation (Capitaine+, 2006)
High precision methods for locating the celestial intermediate pole and origin.
Capitaine N., Wallace P.T.
<Astron. Astrophys. 450, 855 (2006)>
=2006A&A...450..855C 2006A&A...450..855C
ADC_Keywords: Positional data ; Ephemerides ; Earth
Keywords: astrometry - reference systems - ephemerides - celestial mechanics -
time
Abstract:
The precession-nutation transformation describes the changing
directions on the celestial sphere of the Earth's pole and an adopted
origin of right ascension. The coordinate system for the celestial
sphere is the geocentric celestial reference system, and the two
directions are the celestial intermediate pole (CIP) and the celestial
intermediate origin (CIO), the latter having supplanted the equinox
for this purpose following IAU resolutions in 2000. The celestial
coordinate triad based on the CIP and CIO is called the celestial
intermediate reference system; the prediction of topocentric
directions additionally requires the Earth rotation angle (ERA), the
counterpart of Greenwich sidereal time (GST) in the former equinox
based system.
The purpose of this paper is to review the different ways of
calculating the CIP and CIO directions to precisions of a few
microarcseconds over a time span of several centuries, meeting the
requirements of high-accuracy applications.
Description:
Various implementations are described, their theoretical bases
compared and the relationships between the expressions for the
relevant parameters are provided. Semi-analytical and numerical
comparisons have been made, based on the P03 precession and the IAU
2000A nutation, with slight modifications to the latter to make it
consistent with P03.
Methods based on the recent P03 precession model can be found
in Capitaine et al. (2003A&A...412..567C 2003A&A...412..567C, 2005A&A...432..355C 2005A&A...432..355C).
Tables 5-11 contain the coefficients in microarcseconds (uas) of the
series developments (i.e. Fourier and Poisson terms) as functions of
(terrestrial) time t (expressed in centuries since J2000.0) for the
quantities s (Eq. (53)), s+XY/2 (Eq. (58)), s+XY/2+D (Eq. (60)),
EO+Dpsi*cos(epsilon_A) (where EO is given by Eq. (69)), x_{CIO},
y_{CIO}, z_{CIO} (Eq. (70)), respectively, retaining all terms larger
than 0.1 uas.
The general formula is:
S=Sum{on i}[Sum{j=0,5}[(Sji)*tj*sin(ARG)+(Cji*cos(ARG)]*tj]]
where:
ARG = nl*l + nl'*l' + nF*F + nD*D + nOm*Om +nLMe*LMe + nLV*LV + nLE*LE
+ nLMa*LMa + nLJ*LJ + nLS*LS + nLU*LU + nLN*LN +npa*pa
l, l', F, D, Om, LMe, LV, LE, LMa, LJ, LS, LU, LN, pa being the
fundamental lunisolar and planetary arguments of the nutation theory.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sp03.dat 95 177 Terms in the series development for the quantity
s based on P03 precession and IAU 2000A nutation
(table 5 of the paper)
sxy2p03.dat 95 72 Terms in the series development for the quantity
s+XY/2 based on P03 precession and IAU 2000A
nutation (table 6 of the paper)(06-Nov-2006 version)
sxy2dp03.dat 95 42 Terms in the series development for the quantity
s+XY/2+D based on P03 precession and IAU 2000A
nutation (table 7 of the paper)
eep03.dat 95 39 Terms in the series development for the quantity
EO+Dpsi*cos(epsilon_A) based on P03 precession
and IAU 2000A nutation (table 8 of the paper)
xciop03.dat 95 263 Terms in the series development for the quantity
x_CI0 based on P03 precession and IAU 2000A
nutation (table 9 of the paper)
yciop03.dat 95 72 Terms in the series development for the quantity
y_CI0 based on P03 precession and IAU 2000A
nutation (table 10 of the paper)
zciop03.dat 95 1607 Terms in the series development for the quantity
z_CI0 based on P03 precession and IAU 2000A
nutation (table 11 of the paper)
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See also:
J/A+A/400/1145 : IAU 2000A precession-nutation (Capitaine+, 2003)
J/A+A/406/1135 : UT1 definitions in IAU 2000 (Capitaine+, 2003)
J/A+A/355/398 : Celestial Ephemeris Origin definition (Capitaine+, 2000)
Byte-by-byte Description of file: *.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- N Number of records of order j
5- 6 I2 --- j Order of the Poisson term (power of t)
7- 11 I5 --- i Term number i
12- 23 F12.2 uas Sji (Sj)i coefficient, in µas
24- 39 F16.2 uas Cji (Cj)i coefficient, in µas
40- 43 I4 --- nl Mean anomaly of the Moon coefficient
44- 47 I4 --- nl' Mean anomaly of the Sun coefficient
48- 51 I4 --- nF L-Omega (L: Mean longitude of the Moon)
coefficient
52- 55 I4 --- nD Mean elongation from the Moon to the Sun
coefficient
56- 59 I4 --- nOm Mean longitude of the ascending node of
the Moon (Omega) coefficient
60- 63 I4 --- nLMe Mean longitude of Mercury coefficient
64- 67 I4 --- nLV Mean longitude of Venus coefficient
68- 71 I4 --- nLE Mean longitude of the Earth coefficient
72- 75 I4 --- nLMa Mean longitude of Mars coefficient
76- 79 I4 --- nLJ Mean longitude of Jupiter coefficient
80- 83 I4 --- nLS Mean longitude of Saturn coefficient
84- 87 I4 --- nLU Mean longitude of Uranus coefficient
88- 91 I4 --- nLN Mean longitude of Neptune coefficient
92- 95 I4 --- npa Accumulated general precession in
longitude coefficient
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Acknowledgements: Nicole Capitaine, n.capitaine(at)obspm.fr
History: File sxy2p03.dat corrected on 06-Nov-2006 (from author)
(End) Patricia Vannier [CDS] 13-Apr-2006