\documentstyle{article}
\title{
	Astrometry of Solar System Objects observed by Hipparcos.}
                  \author{D. Hestroffer \\
Bureau des Longitudes, 77 Av. Denfert Rochereau\\
 F-75014 Paris, France}
\date{}

\begin{document}
\maketitle
The ESA Hipparcos satellite not only yields great precision results for star positions
  and proper motions, but it also provides valuable results on minor planets or
 natural satellites photometric and astrometric data. Observations of 48 asteroids, J\,II-Europa, S\,VI-Titan and S\,VIII-Iapetus  were made around the quadratures, from november 1989 to march  1993. The reduction of the observed
 positions to astrometric directions is developed. This reduction has to take into
 account small effects up to the milli-arcsecond level, which is uncommon for
 observations of these objects. A twenty seconds averaged normal place  is defined, providing thus positions accurate to a few hundredth of arcseconds, and relative to a very precise and homogeneous reference frame.


\end{document}

