Search Publications
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.
Double star CCD astrometry and photometry
Irwin, M. J.; Argue, A. N.; Lampens, P.
About 3000 CCD measurements of double stars have been made in one or both filters V and R on the 1m Jacobus Kapteyn Telescope at La Palma. The stars form part of the INput CAtalogue (INCA) of the astrometric satellite HIPPARCOS, and require both astrometry and photometry in order to facilitate reduction of the HIPPARCOS measurements. The primary c…
Améliorations des positions des etoiles Hipparcos par l'utilisation des observations ``star-mapper''
Mignard, F.; Donati, F.; Falin, J. L. +2 more
Results on star-mapper data for attitude determination based on observations carried out over fifteen reference great circle's (RGC) are presented and discussed. Precision on the three-angle attitude reconstruction is of the order of 60 milli-arcsec along-scan and 100 and 180 milli-arcsec normal-to-scan. With this first year data, it is possible t…
Infrared and radio astronomy, and astrometry. Proceedings. Symposia 7, 8 and Topical Meeting of the COSPAR Interdisciplinary Scientific Commission E (Meeting E5) of the COSPAR 28. Plenary Meeting: Infrared and radio astronomy, and astrometry, The Hague (Netherlands), 25 Jun - 6 Jul 1990.
Perryman, M. A. C.; Smoot, G. F.; Wesselius, P. R. +2 more
Contents: 1. Astrometry from space (Symposium 7). 2. The infrared and submillimeter universe at high redshift (Symposium 8). 3. Space VLBI (Meeting E5).