Double stars measured here are either long-period binaries for
which the last observation is old, or stars previously observed by us
and for which the companion's position was measured far from the predicted value
(Aristidi et al. 1997b).
Some stars were also selected because their orbit parameters are very uncertain.
Two of these double stars were recently discovered as double: MOAI 1
(SAO 12917)
observed in December 1995 (Carbillet et al. 1996, 1998b),
and Cyg discovered by Hipparcos (The Hipparcos
Catalogue, 1997).
Multiple stars were selected from the Multiple Star Catalogue
(Tokovinin 1997).
All of them present a lack of measurement: unknown orbits,
unknown spectral classes of the components,
companion suspected from other observational techniques (spectroscopy). These stars were selected together
with A.A. Tokovinin.
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