  We compute all the top intersection numbers of divisors on the total space of
the Poincare bundle restricted to the product of a curve and the abelian
variety. We use these computations to find the class of the universal theta
divisor and $m$-theta divisor inside the universal corank 1 semiabelian variety
-- the boundary of the partial toroidal compactification of the moduli space of
abelian varieties. We give two computational examples: we compute the boundary
coefficient of the Andreotti-Mayer divisor (computed by Mumford but in a much
harder and ad hoc way), and the analog of this for the universal $m$-theta
divisor.
