  In the study of moduli spaces defined by the anti-self-dual (ASD) Yang-Mills
equations on SU(2) or SO(3) bundles over closed oriented Riemannian 4-manifolds
M, the bubble tree compactification was defined. In this paper, we apply this
technique to 4-orbifolds of the form M/Z_{\alpha} satisfying a certain
condition to get a bubble tree compactification of the instanton moduli space
on this particular kind of 4-orbifolds.
