This short note was published via the 'old-fashioned' process, and I do not have it in TeX. Here is the abstract:
We study the moduli stack M of SL(2)-bundles with connections on P^{1}. These connections are assumed to have poles of the first order at n points, and the conjugacy classes of their residues are fixed. We compute the Picard group of M. In the case of four points, we compute the cohomology groups of invertible sheaves on M.