  We consider the partition function of the boundary $OSp(2S+2|2S)$ coset sigma
model on an annulus, based on the lattice regularization introduced in the
companion paper. Using results for the action of $OSp(2S+2|2S)$ and $B_L(2)$ on
the corresponding spin chain, as well as mini-superspace and small $g_\sigma^2$
calculations, we conjecture the full spectrum and set of degeneracies on the
entire critical line. Potential relationship with the $OSp(2S+2|2S)$
Gross-Neveu model is also discussed.
