I/311Hipparcos, 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..653VADC_Keywords: Positional data ; Proper motions ; Parallaxes, trigonometric ; Photometry ; Fundamental catalogMission_Name: HipparcosKeywords: space vehicles: instruments - methods: data analysis - catalogs - astrometry - instrumentation: miscellaneousAbstract: 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:

FileName Lrecl Records Explanations

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

Note on hipvim.dat: solution for double stars having one variable component.

See also: I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)Byte-by-byte Description of file: hip2.dat

Bytes Format Units Label Explanations

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)

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 systemNote (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

Byte-by-byte Description of file: hip7p.dat

Bytes Format Units Label Explanations

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)

Byte-by-byte Description of file: hip9p.dat

Bytes Format Units Label Explanations

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)

Byte-by-byte Description of file: hipvim.dat

Bytes Format Units Label Explanations

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)

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(m_{r}-m))) where m_{r}is the reference magnitude of the binary and m the observed magnitude of the binary, and dexp the decimal exponentiation (dexp(x) = 10^{x})

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 U_{i}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, UKReferences: 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

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