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HIPNEWCAT - Hipparcos New Astrometric Catalog

HEASARC
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Overview

A new reduction of the astrometric data as produced by the Hipparcos mission has been published, claiming accuracies for nearly all stars brighter than Hipparcos magnitude H_p = 8 to be better, by up to a factor 4, than in the original catalog. The new Hipparcos astrometric catalog has been 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 of the Hipparcos Catalog are explained in the reference paper.

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 catalog is explained. The formal errors on the parallaxes for the new catalog are confirmed. The presence of a small amount of additional noise, though unlikely, cannot be ruled out.

The new reduction of the Hipparcos astrometric data provides an improvement by a factor 2.2 in the total weight compared to the Hipparcos catalog published in 1997, and, according to the author, provides much improved data for a wide range of studies on stellar luminosities and local galactic kinematics.

Note that this catalog version is slightly different from the one 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 data archived at the CDS (between June and 15 September 2008) also contained errors which were corrected after this date.


Catalog Bibcode

2007A&A...474..653V

References

Hipparcos, the New Reduction of the Raw Data
     van Leeuwen F.
    <Astron. Astrophys. 474, 653 (2007)>
    =2007A&A...474..653V
Hipparcos, the New Reduction of the Raw Data
     van Leeuwen F.
    <Astrophysics & Space Science Library, Vol. 350>
    =2007ASSL..350.....V
The Hipparcos Catalogue
     Perryman, M.A.C. et al.
    <Astron. Astrophys. 323, L49 (1997)>
    =1997A&A...323L..49P

Provenance

This table was created by the HEASARC in August 2009 based on the CDS Catalog I/311 file hip2.dat, "the Astrometric Catalogue".

Parameters

HIP_Number
The Hipparcos source number or identifier, as in the original Hipparcos Catalog.

Name
The name of the star in the recommended format for Hipparcos stars, as created by concatenating the prefix 'HIP ' and the Hipparcos source number or identifier, as in the original Hipparcos Catalog.

New_Solution_Type
The solution type in the new reduction. This is number between 0 and 115, 10 x d + s, consisting of two parts d and s where s describes the type of solution adopted as follows:

        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)
  
where the above-mentioned files can be found at http://cdsarc.u-strasbg.fr/ftp/cats/I/311/, and d describes the presence of peculiarities, as a combination of values, as follows:
        0 = single star
        1 = double star
        2 = variable in the system with amplitude > 0.2 mag
        4 = astrometry refers to the photocenter
        8 = measurements concern the secondary (fainter) in the double system
  

Old_Solution_Type
The solution type in the old reduction. This is number between 0 and 5, 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
  

Number_Components
The number of stellar components.

RA
The Right Ascension of the star in the selected equinox for epoch 1991.25. This was given in the ICRS reference system (similar but not identical to J2000 equator) in the original published catalog (thus the HEASARC recommends that equinox 2000 should be specified to avoid inaccuracies due to the non-rigorous HEASARC coordinate precession algorithm) and in radians, to a precision of 10-10 radians.

Dec
The Declination of the star in the selected equinox for epoch 1991.25. This was given in the ICRS reference system (similar but not identical to J2000 equator) in the original published catalog (thus the HEASARC recommends that equinox 2000 should be specified to avoid inaccuracies due to the non-rigorous HEASARC coordinate precession algorithm) and in radians, to a precision of 10-10 radians.

LII
The Galactic Longitude of the star.

BII
The Galactic Latitude of the star.

Parallax
The stellar trigonometric parallax, pi, in units of milliarcseconds (mas): thus to calculate the stellar distance D in parsecs, D = 1000/pi. The estimated parallax is given for every star, even if it appears to be insignificant or negative.

PM_RA
The proper motion component in the RA direction expressed in milliarcseconds per Julian year (mas/yr), and given with respect to the ICRS reference system.

PM_Dec
The proper motion component in the Declination direction expressed in milliarcseconds per Julian year (mas/yr), and given with respect to the ICRS reference system.

RA_Error
The formal error in the Right Ascension given at the catalog epoch, J1991.25, and expressed in milliarcseconds.

Dec_Error
The formal error in the Declination given at the catalog epoch, J1991.25, and expressed in milliarcseconds.

Parallax_Error
The formal error in the stellar parallax, in milliarcseconds (mas).

PM_RA_Error
The formal error in the proper motion component in the RA direction expressed in milliarcseconds per Julian year (mas/yr).

PM_Dec_Error
The formal error in the proper motion component in the Decination direction expressed in milliarcseconds per Julian year (mas/yr).

N_Obs_HIP_Mag
The number of observations of the Hipparcos magnitude H_p: this is the number of photometric observations (or field transits) used for the construction of the median, standard error, and scatter in H_P

Quality_Fit
The goodness-of-fit statistic: this number indicates the goodness of fit of the astrometric solution.

Reject_Percent
The percentage of data that had to be rejected in order to obtain an acceptable solution.

Cosmic_Dispersion
The cosmic dispersion that was added (stochastic solution).

Suppl_Cat_Flag
This flag is set to a non-zero integer if there is an entry for the star in question in one of the supplemental Hipparcos catalogs.

HIP_Mag
The median magnitude H_P of the star in the Hipparcos photometric system, and defined on the basis of the accepted observations (or field transits) for a given star.

HIP_Mag_Error
The standard error of the median magnitude H_P of the star.

Scat_HIP_Mag
The scatter of the H_P observations.

Var_Data_Annex
This flag is set to a non-zero integer if there is an entry for the star in question in the Variability Annex to the Hipparcos Catalog.

BV_Color
The (B-V) color index of the star, in, or reduced to, the Johnson UBV system.

BV_Color_Error
The formal error of the (B-V) color index.

VI_Color
The Cousins V-I color index of the star.

UT_Weight_Matrix
The upper-triangular weight matrix U of the astrometric solution. U is related to the covariance matrix C by C-1 = ~U U, where ~U represents transposed U. The elements U_i forming the upper triangular matrix are stored in the order depicted below:

           +-                         -+
           |  (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, parallax, pm_RA, pm_Dec, and derivatives of proper motions for 7- and 9-parameter solutions.

Contact Person

Questions regarding the HIPNEWCAT database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 3-Aug-2009