  In this article we prove that the full automorphism group of the baby-monster
vertex operator superalgebra constructed by Hoehn is isomorphic to 2xB, where B
is the baby-monster sporadic finite simple group and determine irreducible
modules for the baby-monster vertex operator algebra. Our result has many
corollaries. In particular, we can prove that the Z_2-orbifold construction
with respect to a 2A-involution of the Monster applied to the moonshine vertex
operator algebra yields the moonshine vertex operator algebra itself again.
