Density functional, quadratic configuration interaction and electron propagator calculations have yielded structures, isomerization energies, and anion vertical electron detachment energies pertaining to Al3On- and Al3On, where n = 1, 2, or 3. These data suffice for an accurate assignment of recent anion photoelectron spectra. Peaks whose relative intensities vary with experimental conditions of ion preparation and transport are associated with isomers whose energies are close to those of the lowest singlet structures. Dyson orbitals associated with the lowest electron detachment energies are dominated by Al-centered functions with antibonding relationships to nearby O centers.