| Hipparcos New Reduction: The Astrometric Catalogue |
| 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. 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. 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. 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. Required constraints:
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| Name | Type | Length | Unit | Description | Default Value | Unified Content Descriptor |
|---|---|---|---|---|---|---|
| hip | int | 4 | Hipparcos identifier | meta.main;meta.id | ||
| ic | int | 4 | Entry in one of the supplementary catalogues | meta.id.cross | ||
| ra | float | 8 | degrees | Right Ascension in the ICRS at epoch 1991.25 | meta.main;pos.eq.ra | |
| dec | float | 8 | degrees | Declination in the ICRS at epoch 1991.25 | meta.main;pos.eq.dec | |
| ra_rad | float | 8 | radians | Right Ascension in the ICRS at epoch 1991.25 | pos.eq.ra | |
| de_rad | float | 8 | radians | Declination in the ICRS at epoch 1991.25 | pos.eq.dec | |
| plx | float | 8 | milliarcseconds | Parallax | pos.parallax | |
| pm_ra | float | 8 | milliarcseconds/year | Proper motion in Right Ascension | pos.eq.ra;pos.pm | |
| pm_de | float | 8 | milliarcseconds/year | Proper motion in Declination | pos.eq.dec;pos.pm | |
| e_ra_rad | float | 8 | milliarcsec | Formal error on ra_rad | pos.eq.ra;stat.error | |
| e_de_rad | float | 8 | milliarcsec | Formal error on de_rad | pos.eq.dec;stat.error | |
| e_plx | float | 8 | milliarcsec | Formal error on parallax | pos.parallax;stat.error | |
| e_pm_ra | float | 8 | milliarcsec/year | Formal error on pm_ra | pos.eq.ra;pos.pm;stat.error | |
| e_pm_de | float | 8 | milliarcsec/year | Formal error on pm_de | pos.eq.dec;pos.pm;stat.error | |
| f1 | int | 4 | Percentage rejected data | arith.ratio;stat.value | ||
| f2 | float | 8 | Goodness of fit | stat.fit.goodness | ||
| nc | int | 4 | Number of components | meta.number | ||
| ntr | int | 4 | Number of field transits used | meta.id;obs.field | ||
| u3 | float | 8 | Upper-triangular weight matric element 3 | stat.weight | ||
| u4 | float | 8 | Upper-triangular weight matric element 4 | stat.weight | ||
| u5 | float | 8 | Upper-triangular weight matric element 5 | stat.weight | ||
| u6 | float | 8 | Upper-triangular weight matric element 6 | stat.weight | ||
| u7 | float | 8 | Upper-triangular weight matric element 7 | stat.weight | ||
| u8 | float | 8 | Upper-triangular weight matric element 8 | stat.weight | ||
| u9 | float | 8 | Upper-triangular weight matric element 9 | stat.weight | ||
| sn | int | 4 | Solution type in the New Reduction | meta.id;stat.fit | ||
| so | int | 4 | Solution type in the old reduction | meta.id;stat.fit | ||
| var | float | 8 | Cosmic dispersion added (stochastc solution) | stat.fit.residual | ||
| u1 | float | 8 | Upper-triangular weight matric element 1 | stat.weight | ||
| u2 | float | 8 | Upper-triangular weight matric element 2 | stat.weight | ||
| u10 | float | 8 | Upper-triangular weight matric element 10 | stat.weight | ||
| u11 | float | 8 | Upper-triangular weight matric element 11 | stat.weight | ||
| u12 | float | 8 | Upper-triangular weight matric element 12 | stat.weight | ||
| u13 | float | 8 | Upper-triangular weight matric element 13 | stat.weight | ||
| u14 | float | 8 | Upper-triangular weight matric element 14 | stat.weight | ||
| u15 | float | 8 | Upper-triangular weight matric element 15 | stat.weight | ||
| hp_mag | float | 8 | mag | Hipparcos magnitude | em.opt;phot.mag | |
| b_v | float | 8 | mag | B-V colour index | phot.color;em.opt.B;em.opt.V | |
| v_i | float | 8 | mag | V-I colour index | phot.color;em.opt.V;em.opt.I | |
| e_hp_mag | float | 8 | mag | Error on mean Hipparcos magnitude | em.opt.V;phot.mag;stat.error | |
| e_b_v | float | 8 | mag | Formal error on B-V colour index | em.opt;phot.colour;stat.error | |
| s_hp | float | 8 | mag | Scatter in Hipparcos magnitudes | stat.error;phot.mag;em.opt | |
| va | int | 4 | Reference to variability annex | meta.note | ||
| cx | float | 8 | unit vector of spherical co-ordinates | pos.distance;pos.cartesian.x | ||
| cy | float | 8 | unit vector of spherical co-ordinates | pos.distance;pos.cartesian.y | ||
| cz | float | 8 | unit vector of spherical co-ordinates | pos.distance;pos.cartesian.z | ||
| htmID | bigint | 8 | Hierarchical Triangular Mesh (HTM) index, 20 deep, for equatorial co-ordinates | pos.eq | ||
| Total length | 344 |