- ID:
- ivo://CDS.VizieR/I/311
- Title:
- Hipparcos, the New Reduction
- Short Name:
- I/311
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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.
1 - 4 of 4
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/I/246
- Title:
- The ACT Reference Catalog
- Short Name:
- I/246
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The U.S. Naval Observatory has completed the compilation of the ACT Reference Catalog, containing 988,758 stars covering the entire sky. The motivation behind the ACT was to provide accurate proper motions for the majority of the stars in the Tycho Catalogue (ESA SP-1200). To do this, positions from new reductions of the Astrographic Catalogue (AC 2000) were combined with those of Tycho. The large epoch span between the two catalogs yields proper motions about an order of magnitude more accurate than those published in the Tycho Catalogue. The astrometric data contained in the ACT Reference Catalog include positions, proper motions and error estimates. These are on the Hipparcos System (J2000.0) for epoch J2000.0. Photometric data (B and V) from Tycho are included. Additionally, cross references to the Tycho, AC 2000, Bonner Durchmusterung (BD), Cordoba Durchmusterung (CD), Cape Durchmusterung (CPD), Henry Draper (HD) and Hipparcos Catalogues are given.
- ID:
- ivo://CDS.VizieR/I/239
- Title:
- The Hipparcos and Tycho Catalogues
- Short Name:
- I/239
- Date:
- 18 Nov 2021 11:08:10
- Publisher:
- CDS
- Description:
- The Hipparcos and Tycho Catalogues are the primary products of the European Space Agency's astrometric mission, Hipparcos. The satellite, which operated for four years, returned high quality scientific data from November 1989 to March 1993. Each of the catalogues contains a large quantity of very high quality astrometric and photometric data. In addition there are associated annexes featuring variability and double/multiple star data, and solar system astrometric and photometric measurements. In the case of the Hipparcos Catalogue, the principal parts are provided in both printed and machine-readable form (on CDROM). In the case of the Tycho Catalogue, results are provided in machine-readable form only (on CDROM). Although in general only the final reduced and calibrated astrometric and photometric data are provided, some auxiliary files containing results from intermediate stages of the data processing, of relevance for the more-specialised user, have also been retained for publication. (Some, but not all, data files are available from the Centre de Donnees astronomiques de Strasbourg.) The global data analysis tasks, proceeding from nearly 1000 Gbit of raw satellite data to the final catalogues, was a lengthy and complex process, and was undertaken by the NDAC and FAST Consortia, together responsible for the production of the Hipparcos Catalogue, and the Tycho Consortium, responsible for the production of the Tycho Catalogue. A fourth scientific consortium, the INCA Consortium, was responsible for the construction of the Hipparcos observing programme, compiling the best-available data for the selected stars before launch into the Hipparcos Input Catalogue. The production of the Hipparcos and Tycho Catalogues marks the formal end of the involvement in the mission by the European Space Agency and the four scientific consortia. For more complete and detailed information on the data, the user is advised to refer to Volume 1 ("Introduction and Guide to the Data", ESA SP-1200) of the printed Hipparcos and Tycho Catalogues. The user should also note that in order to convert the Double and Multiple Systems (Component solutions) data file hip_dm_c.dat into FITS format it is first necessary to filter the file according to whether the entry is a component record (identified by COMP in field DCM5) or a correlation record (identified by CORR in field DCM5) because of the different structures of the respective records. On a Unix system this can be achieved as follows: grep COMP hip_dm_c.dat > h_dm_com.dat grep CORR hip_dm_c.dat > h_dm_cor.dat The catalogue description file (this file) gives the relevant information for converting the main data files, including h_dm_cor.dat and h_dm_com.dat, into FITS format. The machine readable data files (i.e. those available on CD-ROM and the subset available from the CDS) contain several extra fields in addition to the data from the printed catalogue. These fields are identified by the letter `M' in the data label (e.g. the field DGM1 contains data only available in the machine readable file hip_dm_g.dat).
- ID:
- ivo://CDS.VizieR/I/250
- Title:
- The Tycho Reference Catalogue
- Short Name:
- I/250
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Tycho Reference Catalogue (TRC) contains high-quality positions and proper motions for 990182 stars of the Tycho Catalogue. The proper motions were derived from Tycho positions and Astrographic Catalogue positions reduced to the Hipparcos system. The median accuracy of the TRC position components is 40 mas at J1991.25. The median accuracy of the proper motion is about 2.5 mas/yr. Systematic errors are less than about 1.0 mas(/yr). The quality of the proper motions in TRC is assessed by comparison with the Hipparcos and Tycho Catalogues. Comparison with the recent ACT Catalogue which is based on an independent reduction of the same observations as used for constructing the TRC is reported.
