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Polarimetric investigatio, on interstellar dust within 50 PC from the sun.
Leroy, J. L.
We have analyzed the polarization catalogue, for 1000 stars closer than 50 Pc, which has been presented in a companion paper. Although the accuracy of the measurements is generally very good (better than 0.02% for more than 700 stars), the catalogue contains essentially unpolarized stars, which is to be related to the well known depletion of dust …
Hubble Space Telescope Astrometric Observations of Pre-Main Sequence Stars from the HIPPARCOS Program
Badiali, M.; Cardini, D.; Emanuele, A. +6 more
We report on the first set of high angular resolution observations with Fine Guidance Sensor (FGS) #3 aboard the Hubble Space Telescope of a sample of T-Tauri and Herbig Ae/Be pre-main sequence stars, which have also been observed with the HIPPARCOS satellite. Among the 5 Ae/Be stars observed so far of particular interest is the new double HIPPARC…
HIPPARCOS link with Carte du Ciel triple images.
Tucholke, H. -J.; Brosche, P.; Guibert, J. +3 more
This study for the first time investigates the possibility of deriving astrometric positions for bright stars on Carte du Ciel (CdC) plates, whose triple images are not separable. The field from the Bonn Hipparcos Extragalactic Link Programme with the BL Lac object OJ 287 has been selected. The triple images on the CdC plate were modelled by three…
The Hyades distance and white dwarf constraints.
Weidemann, V.
It is demonstrated how recent determinations of surface gravity and gravitational red shifts for the Hyades white dwarfs constrain the distance of the cluster for which very discrepant values between trigonometric and kinematic results are presently discussed. If the surface gravity data are correct, the Hyades modulus must be close to m - M = 3.3…
Systematic deformations of the apparent almucantar as derived from Danjon astrolabes in Paris and Santiago de Chile
Pesek, I.; Vondrak, J.; Chollet, F. +1 more
Systematic deformations of apparent almucantar based on long series of observations with Danjon astrolabes in Paris and Santiago de Chile are derived. It is shown that their amplitudes of order of 0".1 - 0".2 have significant seasonal character. Comparison of the results based on two different catalogs (FK4 and FK5) make us believe that at least 5…
A global analysis method for astrolabe observations
Chollet, F.
In a previous paper (Chollet & Najid 1992), we gave the general principles of a new global method to analyze the astrolabe observations. The fundamental equation was obtained from the classical one in which the corrections to the star positions at the observational epoch are replaced by developments that contain the corrections to the star pos…