1995A&A...304..132R -
Astronomy and Astrophysics, volume 304, 132-140 (1995/12-1)
Schmidt plate astrometric reductions using preliminary Hipparcos and Tycho data.
ROBICHON N., TURON C., MAKAROV V.V., PERRYMAN M.A.C., HOG E., FROESCHLE M., EVANS D.W., GUIBERT J., LE POOLE R.S., VAN LEEUWEN F., BASTIAN U. and HALBWACHS J.L.
Abstract (from CDS):
New reductions of Schmidt plate measurements have been performed, using preliminary Hipparcos and Tycho data for the astrometric reference stars. The measurements reported here have been obtained with the MAMA automatic measuring machine of the Centre d'Analyse des Images in Paris. The Hipparcos data considered, the `combined 30-month solution', or `H30', is a preliminary catalogue derived from the analysis of the first 30 months of data (out of a total of 37 months), and represent the merging of the intermediate FAST and NDAC Consortia's sphere solutions. The Tycho data considered here, referred to as `T30d', are derived from the preliminary analysis of the first 30 months of Hipparcos star mapper data. The preliminary Hipparcos and Tycho data are of unprecedent accuracy, and have been used to show that the ultimate accuracy which can be obtained on positions derived from Schmidt plates measurements is about 0.07arcsec, compared with errors of at best 0.15arcsec but more typically about 0.3arcsec obtained on the basis of previously-available catalogues. The best accuracy is obtained using Tycho stars which, although of lower individual accuracy than the Hipparcos positions, are very numerous (the Tycho Catalogue will include about one million stars) and thus allow a very good modelling of Schmidt plate field distortions. This accuracy is attainable for plates taken at epochs close to the Hipparcos mid-mission epoch. Plans to determine accurate proper motions for Tycho Catalogue stars using Tycho positions and, for example, Astrographic Catalogue data, will allow an extension of this possibility to a much wider range of plate epochs.
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Journal keyword(s):
astrometry - methods: data analysis
Simbad objects:
6
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