Rank-stable limit of completed moduli spaces of instantons

Nakajima introduced a resolution of singularities of the Donaldson-Uhlenbeck completion of the moduli space of based instantons over $S^4$. For $k\leq 4$, we extend this result to $\mathbb P^2$ and compute, in the rank-stable limit, the homotopy type of these spaces by showing that, in this limit, these constructions yield universal bundles.