I/311 Hipparcos, the New Reduction (van Leeuwen, 2007)
Hipparcos, the new Reduction of the Raw data
van Leeuwen F.
<Astron. Astrophys. 474, 653 (2007)>
=2007A&A...474..653V 2007A&A...474..653V
ADC_Keywords: Positional data ; Proper motions ; Parallaxes, trigonometric ;
Photometry ; Fundamental catalog
Mission_Name: Hipparcos
Keywords: space vehicles: instruments - methods: data analysis - catalogs -
astrometry - instrumentation: miscellaneous
Abstract:
A new reduction of the astrometric data as produced by the Hipparcos
mission has been published, claiming accuracies for nearly all stars
brighter than magnitude Hp=8 to be better, by up to a factor 4, than
in the original catalogue.
The new Hipparcos astrometric catalogue is checked for the quality of
the data and the consistency of the formal errors as well as the
possible presence of error correlations. The differences with the
earlier publication are explained.
Methods. The internal errors are followed through the reduction
process, and the external errors are investigated on the basis of a
comparison with radio observations of a small selection of stars, and
the distribution of negative parallaxes. Error correlation levels are
investigated and the reduction by more than a factor 10 as obtained in
the new catalogue is explained.
Results. The formal errors on the parallaxes for the new catalogue are
confirmed. The presence of a small amount of additional noise, though
unlikely, cannot be ruled out.
Conclusions. The new reduction of the Hipparcos astrometric data
provides an improvement by a factor 2.2 in the total weight compared
to the catalogue published in 1997, and provides much improved data
for a wide range of studies on stellar luminosities and local galactic
kinematics.
Notice:
The files included are slightly different from the ones published in
the book, as an error that sometimes affected the goodness of fit
value for the solution was corrected. The first version of these files
(between June and 15 September 2008) also contained errors corrected
after this date.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
hip2.dat 276 117955 The Astrometric Catalogue
hip7p.dat 129 1338 Seven-parameter solutions
hip9p.dat 274 104 Nine-parameter solutions
hipvim.dat 129 25 *Variability-induced (VIM) solutions
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Note on hipvim.dat: solution for double stars having one variable component.
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See also:
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
Byte-by-byte Description of file: hip2.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HIP Hipparcos identifier
8- 10 I3 --- Sn [0,159] Solution type new reduction (1)
12 I1 --- So [0,5] Solution type old reduction (2)
14 I1 --- Nc Number of components
16- 28 F13.10 rad RArad Right Ascension in ICRS, Ep=1991.25
30- 42 F13.10 rad DErad Declination in ICRS, Ep=1991.25
44- 50 F7.2 mas Plx Parallax
52- 59 F8.2 mas/yr pmRA Proper motion in Right Ascension
61- 68 F8.2 mas/yr pmDE Proper motion in Declination
70- 75 F6.2 mas e_RArad Formal error on RArad
77- 82 F6.2 mas e_DErad Formal error on DErad
84- 89 F6.2 mas e_Plx Formal error on Plx
91- 96 F6.2 mas/yr e_pmRA Formal error on pmRA
98-103 F6.2 mas/yr e_pmDE Formal error on pmDE
105-107 I3 --- Ntr Number of field transits used
109-113 F5.2 --- F2 Goodness of fit
115-116 I2 % F1 Percentage rejected data
118-123 F6.1 --- var Cosmic dispersion added (stochastic solution)
125-128 I4 --- ic Entry in one of the suppl.catalogues
130-136 F7.4 mag Hpmag Hipparcos magnitude
138-143 F6.4 mag e_Hpmag Error on mean Hpmag
145-149 F5.3 mag sHp Scatter of Hpmag
151 I1 --- VA [0,2] Reference to variability annex
153-158 F6.3 mag B-V Colour index
160-164 F5.3 mag e_B-V Formal error on colour index
166-171 F6.3 mag V-I V-I colour index
172-276 15F7.2 --- UW Upper-triangular weight matrix (G1)
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Note (1): Solution type.
The solution type is a number 10xd+s consisting of two parts d and s:
- s describes the type of solution adopted:
1 = stochastic solution (dispersion is given in the 'var' column)
3 = VIM solution (additional parameters in file hipvim.dat)
5 = 5-parameter solution (this file)
7 = 7-parameter solution (additional parameters in hip7p.dat)
9 = 9-parameter solution (additional parameters in hip9p.dat)
- d describes peculiarities, as a combination of values:
0 = single star
1 = double star
2 = variable in the system with amplitude > 0.2mag
4 = astrometry refers to the photocenter
8 = measurements concern the secondary (fainter) in the double system
Note (2): as follows:
0 = standard 5-parameter solution
1 = 7- or 9-parameter solution
2 = stochastic solution
3 = double and multiple stars
4 = orbital binary as resolved in the published catalog
5 = VIM (variability-induced mover) solution
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Byte-by-byte Description of file: hip7p.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HIP Hipparcos identifier
8- 12 F5.2 --- Fg Detection statistic
14- 19 F6.2 mas/yr2 dpmRA Acceleration in Right Ascension
21- 26 F6.2 mas/yr2 dpmDE Acceleration in Declination
28- 32 F5.2 mas/yr2 e_dpmRA Formal error on dpmRA
34- 38 F5.2 mas/yr2 e_dpmDE Formal error on dpmDE
39-129 13F7.2 --- UW Upper-triangular weight matrix U16..U28 (G1)
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Byte-by-byte Description of file: hip9p.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HIP Hipparcos identifier
8- 12 F5.2 --- Fg Detection statistic
14- 19 F6.2 mas/yr2 dpmRA Acceleration in Right Ascension
21- 26 F6.2 mas/yr2 dpmDE Acceleration in Declination
28- 33 F6.2 mas/yr3 ddpmRA Acceleration change in Right Ascension
35- 40 F6.2 mas/yr3 ddpmDE Acceleration change in Declination
42- 46 F5.2 mas/yr2 e_dpmRA Formal error on dpmRA
48- 52 F5.2 mas/yr2 e_dpmDE Formal error on dpmDE
54- 58 F5.2 mas/yr3 e_ddpmRA Formal error on ddpmRA
60- 64 F5.2 mas/yr3 e_ddpmDE Formal error on ddpmDE
65-274 30F7.2 --- UW Upper-triangular weight matrix U16..U45 (G1)
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Byte-by-byte Description of file: hipvim.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HIP Hipparcos identifier
8- 12 F5.2 --- Fg Detection statistic
14- 19 F6.2 mas upsRA VIM in Right Ascension (1)
21- 26 F6.2 mas upsDE VIM in Declination (1)
28- 32 F5.2 mas e_upsRA Formal error on upsRA
34- 38 F5.2 mas e_upsDE Formal error on upsDE
39-129 13F7.2 --- UW Upper-triangular weight matrix U16..U28 (G1)
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Note (1): the variability-induced movement is due to the variability
of one component of the binary which changes the position of the
photocenter along the RA (or Dec) axis with the quantity
ups*(1 - dexp(-0.4(mr-m)))
where mr is the reference magnitude of the binary and m
the observed magnitude of the binary, and dexp the decimal
exponentiation (dexp(x) = 10x)
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Global Notes:
Note (G1): The upper-triangular weight matrix U is related to the
covariance matrix C by
C-1 = ∼U U (∼U represents transposed U)
The elements Ui forming the upper triangular matrix are stored as
± -+
| (1) (2) (4) (7) (11) |
| 0 (3) (5) (8) (12) |
| 0 0 (6) (9) (13) |
| 0 0 0 (10) (14) |
| 0 0 0 0 (15) |
± -+
on the astrometric parameters RA, Dec, plx, pmRA, pmDE,
and derivatives of proper motions for 7- and 9-parameter
solutions.
Acknowledgements:
Floor van Leeuwen, Institute of Astronomy, Cambridge University
Cambrisge, UK
References:
Floor van Leeuwen, 2007 "Hipparcos, the New Reduction of the Raw Data"
Astrophysics & Space Science Library #350.
History:
* 09-Jun-2008: Original version (with errors)
* 16-Sep-2008: new files from author
(End) Francois Ochsenbein [CDS] 16-Sep-2008