  In this paper, we will show that one can use certain types of symplectic
homology as an invariant of 3-dimensional Besse manifolds, which are contact
manifolds admitting a periodic Reeb flow and hence allow Seifert fibration
structure. For simplicity, we will assume our contact structures to be trivial
plane bundles. We will also compute Robbin-Salamon indices of periodic Reeb
orbits in Besse manifolds and obtain more precise information about the
symplectic homology. In the computations, invariants of the Seifert fibration
such as the Euler number and the orbifold Euler characteristic play an
important role.
