J/A+A/463/783 Combined astrometric catalogue EOC-3 (Vondrak+, 2007)
Combined astrometric catalogue EOC-3.
Vondrak J., Stefka V.
<Astron. Astrophys. 463, 783 (2007)>
=2007A&A...463..783V 2007A&A...463..783V
ADC_Keywords: Fundamental catalog ; Positional data
Keywords: reference systems - astrometry - catalogs
Abstract:
In the past, we collected the astrometric observations of
latitude/universal time variations made worldwide at 33 observatories.
These observations, referred to Hipparcos Catalogue, were then used to
determine the Earth Orientation Parameters (EOP) at 5-day intervals,
covering the interval 1899.7-1992.0. Later on, new astrometric
catalogues (such as ARHIP or TYCHO-2) appeared as combination of
Hipparcos/Tycho positions with ground-based catalogues. These
catalogues yield more accurate proper motions than the original
Hipparcos Catalogue.
Many of the objects observed in the programmes of monitoring Earth
orientation from the ground are double or multiple systems, having
non-negligible periodic motions. We aim at obtaining a star catalogue
with improved proper motions and quasi-periodic terms reflecting
orbital motions of the stars observed in these programmes.
We used about 4.5 million observations of latitude/universal time
variations, and combined them with the catalogues ARIHIP, TYCHO-2
etc... in order to obtain Earth Orientation Catalogue (EOC). Spectral
analysis of ground-based data is made in order to discover which of
the observed objects display periodic motions, and the method of least
squares is then used to estimate corresponding amplitudes and phases.
The third version of the catalogue, EOC-3, contains 4418 different
objects (i.e., stars, components of double stars, photocenters). Our
attempt leads to a description of more accurate paths of the observed
objects that will be eventually used for another determination of the
Earth Orientation Parameters in the twentieth century.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
eoc3.dat 287 4418 The III version of Earth Orientation Catalogue
--------------------------------------------------------------------------------
See also:
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
I/259 : The Tycho-2 Catalogue (Hog+ 2000)
Byte-by-byte Description of file: eoc3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- Seq Star number
8- 18 F11.5 s RAsec [0/86400[ Right ascension (ICRS, Ep=J2000)
20- 31 F12.4 arcsec DEsec [-324000/324000] Declination (ICRS, Ep=J2000)
33- 40 F8.5 arcsec/yr pmRA Proper motion in right ascension multiplied
by cos(declination) (pmRA*cos(DE))
42- 49 F8.5 arcsec/yr pmDE Proper motion in declination
51- 55 F5.2 yr EpRA Epoch of RA (offset 1900)
57- 61 F5.2 mas e_RAsec rms uncertainty in RA
63- 67 F5.2 mas/yr e_pmRA rms uncertainty in pmRA
69- 73 F5.2 yr EpDE Epoch of DE (offset 1900)
75- 79 F5.2 mas e_DEsec rms uncertainty in DE
81- 85 F5.2 mas/yr e_pmDE rms uncertainty in pmDE
87- 93 F7.4 arcsec plx Trigonometric Parallax
95-100 F6.1 km/s RVel Radial velocity
102-106 F5.2 mag mag Apparent magnitude
108-113 F6.2 yr P1 P1 coefficient (1/f1) (1)
115-119 F5.2 yr P2 P1 coefficient (1/f2) (1)
121-128 F8.4 arcsec CR CR coefficient (1)
130-137 F8.4 arcsec DR DR coefficient (1)
139-146 F8.4 arcsec C1R C1R coefficient (1)
148-155 F8.4 arcsec D1R D1R coefficient (1)
157-164 F8.4 arcsec ER ER coefficient (1)
166-173 F8.4 arcsec FR FR coefficient (1)
175-182 F8.4 arcsec E1R E1R coefficient (1)
184-191 F8.4 arcsec F1R F1R coefficient (1)
193-200 F8.4 arcsec CD CD coefficient (1)
202-209 F8.4 arcsec DD DD coefficient (1)
211-218 F8.4 arcsec C1D C1D coefficient (1)
220-227 F8.4 arcsec D1D D1D coefficient (1)
229-236 F8.4 arcsec ED ED coefficient (1)
238-245 F8.4 arcsec FD FD coefficient (1)
247-254 F8.4 arcsec E1D E1D coefficient (1)
256-263 F8.4 arcsec F1D F1D coefficient (1)
265-270 F6.2 mas e_ARA rms uncertainty in amplitudes of RA (2)
272-277 F6.2 mas e_ADE rms uncertainty in amplitudes of DE (2)
279 I1 --- AE [0/3] Astrometric excellency (3)
281-283 A3 --- CAT Astronomical Catalogue (4)
285 A1 --- BS [ABP] Binary system (5)
287 I1 --- PF [1/3]? How the periods were found out (6)
--------------------------------------------------------------------------------
Note (1): Equation :
A(t) = RAs + [pmRA + CRcos(2πf1t) + DRsin(2πf1t)
+ C1Rcos(4πf1t) + D1Rsin(4πf1t)
+ ERcos(2πf2t) + FRsin(2πf2t)
+ E1Rcos(4πf2t) + F1Rsin(4πf2t)
]/15cos(DEs)
DE(t) = DEs + pmDE + CDcos(2πf1t) + DDsin(2πf1t)
+ C1Dcos(4πf1t) + D1Dsin(4πf1t)
+ EDcos(2πf2t) + FDsin(2πf2t)
+ E1Dcos(4πf2t) + F1Dsin(4πf2t)
f1,f2 ... 1/P1,1/P2
t ... time in years from J2000.0
Note (2): rms uncertainties in amplitudes defined as:
e_ARA = sqrt((CR2 + DR2 + C1R2 + D1R2 + ...)/n)
e_ADE = sqrt((CD2 + DD2 + C1D2 + D1D2 + ...)/n)
where n is number of nonzero amplitudes
Note (3): Astrometric excellency from 3 (highest rank) to 0 (lowest rank)
Note (4): Catalogue that was combined with Earth Orientation observations
as follows:
F61 = Sixth Catalogue of Fundamental Stars I. Cat. I/264
F63 = Sixth Catalogue of Fundamental Stars III. Cat. I/264
GCH = Combination of Hipparcos with Boss' General Catalogue I/113
HIP = Hipparcos Catalogue, Cat. I/239
PPM = Position and Proper Motion catalogue, Cat. I/146 & I/193
TYC = Tycho Catalogue, Cat. I/239
T2H = Tycho-2, Cat. I/259
XXX = 'local' catalogue
Note (5): Binary system as follows:
A = component A
B = component B
P = photocenter
Note (6): How the periods were found out as follows:
1 = The period was found by spectral analysis only.
2 = Period was found both by spectral analysis and in the Sixth
Catalog, their difference was smaller than a 20% relative
tolerance,catalog's period was accepted.
3 = The difference between the two values for the period exceeded
the tolerance, period found by spectral analysis was not
statistically significant, but for the period taken over from
the Sixth Catalog the condition of significance was met.
--------------------------------------------------------------------------------
Historical notes:
* 06-Feb-2007: Original data
* 15-Nov-2007: Corrected table and RA(t) expression, from authors
* 21-Nov-2008: Corrected formula of Note (1) above.
Acknowledgements:
Jan Vondrak, vondrak(at)ig.cas.cz
V. Stefka, stefka(at)ig.cas.cz
(End) Patricia Vannier [CDS] 25-Oct-2006