TYCHO/HIPPARCOS A Successful Mission! First Results and Further Improvements

  • A. Wicenec
Conference paper
Part of the Reviews in Modern Astronomy book series (MOD.ASTRONOMY, volume 4)


The astrometric satellite HIPPARCOS has been launched by an Ariane IV rocket early in the morning of 9-August-1990. The intention of this mission to measure very accurate positions (2 milli-arcsec), trigonometric parallaxes and annual proper motions for about 118,000 selected stars seems to become impracticable after the failure of the apogee boost motor. However it turns out that the difficulties related with the highly elliptic geostationary transfer orbit can be mostly overcome with the socalled ’revised mission’. The degradation of the solar cells and the electronics due to the particles of the van Allen belts have been shown to be much less than even optimistic specialists stated during the first weeks after launch (see for example Jahreiß [1]). With a now expected lifetime of at least three years it is possible to get almost the same quantity and quality of input and output data as expected for the nominal mission. The additional TYCHO project will result in photometric and astrometric data for at least 500,000 possibly up to 1.000.000 stars in the range of 2 ≲ mag B ≲ 11. This is even more than expected before launch and the values given in [1] for the revised mission are fortunately completely outdated.


Linear Filter Bright Star Format Background Nominal Mission Group Crossing 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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    H.Jahreifl: HIPPARCOS After Launch!? The Preparation of the Input Catalogue in Reviews in modern Astronomy 2, Springer 1989 p.72Google Scholar
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    M.A.C. Perryman, H.Hassan (eds.): The HIPPARCOS mission: Pre-launch status, Volume I. The HIPPARCOS Satellite ESA SP-1111, 1989Google Scholar
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    M.A.C. Perry man, H.Hassan (eds.): The HIPPARCOS mission: Pre-launch status, Volume II. The Input Catalogue ESA SP-1111, 1989Google Scholar
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    M.A.C. Perryman, H.Hassan (eds.): The HIPPARCOS mission: Pre-launch status, Volume III. The Data Reductions ESA SP-1111, 1989Google Scholar
  5. 5.
    E.Høg, A.Wicenec TYCHO Assessment, Proceedings of the 28th COSPAR Plenary Meeting, COSPAR Symposium S7, ’Astrometry form Space’ tbp.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1991

Authors and Affiliations

  • A. Wicenec
    • 1
  1. 1.Astronomisches Institut TübingenTübingenFed. Rep. of Germany

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