  Simplified solutions to determine binary elements by astrometry were obtained
in terms of elementary functions (Asada et al. 2004), and therefore require
neither iterative nor numerical methods. In the framework of the simplified
solution, this paper discusses the remaining two parameters of the time of
periastron passage and the longitude of ascending node in order to complete the
solution. We thus clarify a difference between the simplified solution and
other analytical methods.

Astrophysics