| Contents |
| We study the main families of periodic orbits around the
collinear points of the restricted spacial 3 body problem. We construct a resonant
normal form on the central manifold and exploit it to compute bifurcation thresholds
of halo orbits in the whole range of mass parameter $0 \le \mu \le 1/2$ recovering,
as a limit case, the Hill problem. |
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