  With ultracold $^{88}$Sr in a 1D magic wavelength optical lattice, we
performed narrow line photoassociation spectroscopy near the $^1$S$_0 -
^3$P$_1$ intercombination transition. Nine least-bound vibrational molecular
levels associated with the long-range $0_u$ and $1_u$ potential energy surfaces
were measured and identified. A simple theoretical model accurately describes
the level positions and treats the effects of the lattice confinement on the
line shapes. The measured resonance strengths show that optical tuning of the
ground state scattering length should be possible without significant atom
loss.
