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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…The Far Ultraviolet Spectrum of the O4I/N/F Star Zeta-Puppis
Danezis, E.; Laskarides, P. G.; Theodossiou, E.
A detailed list of line identifications of the far UV spectrum of the O4I(n)f star ζ Puppis (HD 66811) in the wavelength range λλ1168–1984 Å recorded on 16 April, 1981 with the International Ultraviolet Explorer (IUE) is presented. The detailed analysis of the radial velocities measured in the same wavelength range is also presented.
Astrometry of Southern Radio Sources
Preston, Robert A.; White, Graeme L.; Gulkis, Samuel +7 more
An overview is presented of a number of astrometry and astrophysics programs based on radio sources from the Parkes 2.7 GHz catalogues. The programs cover the optical identification and spectroscopy of flat-spectrum Parkes sources and the determination of their milliarc-second radio structures and positions. Work is also in progress to tie togethe…
Ultraviolet Observations of a Bright Southern Quasar
Strauss, Michael A.; Kirhakos, Sofia; Fisher, Karl B. +2 more
We present low-resolution ultraviolet spectra of the QSO 09149 - 6206 (z = 0.057) obtained with the International Ultraviolet Explorer. The spectrum shows strong emission lines of Ly α, C IV, C III], Mg II, and Fe II. The Fe II blend centered at 2080 A is unusually strong; this may be a consequence of overcorrection for the 2175 A silicate feature…
The remarkable ultraviolet spectrum of HD 43246
Stickland, D. J.
An Observational Program for a Unified Optical / Radio Reference Frame
White, G.; de Vegt, C.; Johnston, K. J. +4 more
An observational pilot program is described which provides a first step towards the construction of an inertial extragalactic reference frame from optical and radio measurements. Candidate objects will be selected from extragalactic compact radio sources which display optical counterparts. Galactic radio stars will be secondary reference objects. …
Procedures for validating HIPPARCOS astrometric parameters
Lenhardt, H.; Walter, H. G.; Hering, R.
The data flow and logical performance of the Hipparcos software package for determining astrometric parameters are checked using simulated data based on 4560 stars. The results are assessed using statistical criteria and references to external stellar data of confirmed astrometric properties. As a by-product, a reference data set is established fo…
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 soft X-ray variability of NGC 5548.
Kaastra, J. S.
The soft X-ray variability of NGC 5548 is studied using EXOSAT's low energy telescope in conjunction with the channel multiplyer array (CMA). For the first time, the pulse height distribution of the CMA data is used to infer information on the spectral variability. The spectrum of NGC 5548 consists of a hard power law and a soft component. During …
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 …