\documentstyle{article}
    \title{Astrometric observations of high accuracy of asteroids by
                occultations of "Hipparcos" stars.}
        \author{L.K. Kristensen\\
 Institute of Physics and Astronomy   \\ 
         University of Aarhus, DK- 8000 Aarhus C, Danemark.}
\date{}

\begin{document}
\maketitle

  The list of ground-based astrometric observations of high accuracy
should include occultations of stars by asteroids. Even a $\pm 0.2 sec$
timing error of an occultation will for an asteroid with a normal daily
motion tie the position to the star with a  formal error of only $\pm 2
mas$. The value of occultation observations will greatly increase in the
future when the poles of rotation and shapes of the asteroids will be
better know and the observations may be re-reduced from the irregular
limb to the center of mass. This is in sharp contrast to most present
day positions of asteroids which have mean observational errors  of order
$\pm 1"$ and will deteriorate in the future because reference stars and 
often not even the catalogues are stated.
  The most difficult obstacle for occultation observations today is the
very incertain predictions. This will change completely for a given
object as soon as three occultations among the numerous "Tycho" stars
have been observed.


        
\end{document} 
