Search Publications
Hipparcos: Revised mission overview
Perryman, M. A. C.
The Hipparcos astrometry satellite was launched on 8 August 1989, and after spacecraft and payload commissioning, commenced the routine data acquisition phase on 26 November 1989. Having failed to reach its planned geostationary orbit, major revisions in the mission operations had to be performed, although the impact on the final mission accuracie…
Groundbased optical and radio astrometry of Hipparcos extragalactic link objects
Zacharias, N.; Johnston, K. J.; de Vegt, Chr.
The construction of a new extragalactic all-sky reference frame based on groundbased high precision optical and radio astrometry of selected compact radio sources and radio stars has been started in 1987 as a joint longterm project involving several astrometric facilities in both hemispheres. At present this system is based on a masterlist of abou…
Search of the latest non-astrometric Hipparcos stars in the HST guide-star catalogue
Crifo, F.; Grenon, M.; Jahreiss, H. +1 more
During the preparation of the Hipparcos Input Catalogue, about 800 Hipparcos stars remained without reliable positions or with questionable identifications. The Hubble Space Telescope Guide Star Catalogue group at the STScI in Baltimore provided charts (10×10 or 16×16 arcmin) showing all stars in the field down to the limiting magnitude of the GSC…
TYCHO assessment
Hog, E.; Wicenec, A.
The photon counts from the HIPPARCOS star mapper contains significant photometric and astrometric information on at least 400 000 stars in the interval of magnitudes from B=2 to 11. Analysis of the first few weeks of data from this TYCHO experiment on-board the HIPPARCOS satellite has shown that the original expectations can be fulfilled with the …
White dwarfs
Barstow, M. A.
Astronomical observations at EUV (~100-1000Å) and FUV (~1000-2000Å) wavelengths have revolutionised our knowledge of white dwarfs and evolutionarily related objects such as subdwarfs and the nuclei of planetary nebulae. Data obtained principally with the IUE and EXOSAT observatories have revealed the presence of trace elements within white dwarf a…
Hipparcos data reduction overview
Lindegren, L.
The Hipparcos satellite generates about 1011 bytes of scientific data per year. The determination of astrometric and photometric quantities for the observed objects is a large and complicated task. The complexity is largely due to the strong coupling between objects in widely different parts of the sky, superposed by means of the two-wa…
Hipparcos project main reduction operations within the fast consortium
Villenave, M.; Huc, C.; Pieplu, J. L. +1 more
A brief overview of the HIPPARCOS data reduction software system operated at CNES for the FAST consortium is given /1/. The main function of this system is the scientific processing of the HIPPARCOS data, from the photon counts of the stars observed to the astrometric parameters with a very high accuracy of 0.002 arc sec.
The major aspects of…Expected performances of Hipparcos satellite in detecting double star systems
Badiali, M.; Cardini, D.; Emanuele, A. +2 more
The software for automatic extraction of double star parameters from Hipparcos data is tested for different types of star systems with different magnitudes, colours, separations and position angles. the influence of the mission degradation due to shorter available observation time is also examined, by checking the behaviour of the results dependin…
The anomalous cases in the double star data reductions of the Hipparcos mission
Pannunzio, R.
In the present paper, some cases of objects observed by HIPPARCOS and whose signal is ``anomalous'' are considered. In this context, only the double stars giving wrong parameters during the automatic reduction chain, have been considered as ``anomalous''. For each case examined, a new mathematical model has been taken into account and inserted in …
VLBI astrometry and the Hipparcos link to the extragalactic reference frame
Lestrade, J. -F.; Preston, R. A.; Gabuzda, D. C. +1 more
The link between the optical and VLBI extragalactic reference frames is undertaken with a long-term program of differential VLBI astrometric observations of 12 radio stars. The status of the program and an assessment of the astrometric accuracy of these observations are presented.