Gravitational waves have offered us a whole new way of looking at our Universe. So far, we have seen them in the ~10-100 Hz range, and, most recently, in the nanohertz regime. However, there are parts of the frequency space that are currently not covered by any future or planned observations. I will explain how we can use upcoming photometric surveys to bridge the gaps in the spectrum through relative astrometric measurements. Similar to the pulsar timing array measurements, these astrometric measurements rely on the coherent spacetime distortions produced by gravitational waves at Earth. These induce coherent, apparent stellar position changes on the sky. Upcoming photometric surveys will have excellent relative astrometry and timing resolution, which will make them perfect for detecting gravitational waves in the microhertz regime. In this talk, I will discuss this measurement scheme, as well as our concrete steps to develop ideal estimators, and our work to mitigate systematics in real data.