I will first review the classical Kronecker 2^nd limit formula, viewed as a relation between partition functions and Green’s functions in orbifolds of flat space (as discussed for example in arXiv:1407.0027, appendix E). I will then discuss the generalization of this relation to orbifolds of the gravitational plane wave, a Penrose limit of AdS (dual of the BMN limit in gauge theory). This provides a natural one-parameter deformation of Kronecker-Eisenstein series, and more generally of Jacobi-Maass forms. This talk is based on arXiv:1910.02745.