"On a special isogeny of K3 surfaces"

Adrian Clingher, Missouri,

I will discuss a correspondence relating principally polarized complex
abelian surfaces to certain K3 surfaces of high Picard rank, the K3
surfaces polarized by the lattice H+E8+E7. The correspondence has a
Hodge-theoretic origin. However, it can be explained in pure geometric
terms by means of a special isogeny of K3 surfaces.  I will explain
the setting of the isogeny in question and then use this framework to
obtain explicit formulas for the correspondence in terms of genus-two
Siegel modular forms.