GEO and LEO: The Final Frontier for Plutonic FFP Parallax

I show that microlens parallaxes, ₄, can be derived for free-floating planets (FFPs) with masses down to that of Pluto, by combining observations from a satellite in geosynchronous (GEO) orbit with another observatory that is on or near Earth's surface, i. e. , either ground-based or in low Earth orbit (LEO). Because these low-mass FFPs typically have measurements of the angular Einstein radius, ₄, from finite-source effects, such ₄ measurements directly yield the FFP mass M= ₄/ ₄ where is a physical constant. Such Earth-GEO measurements almost perfectly complement Earth-L2 measurements, which extend to higher FFP mass and greater FFP distance. LEO-only observations can yield mass measurement at even smaller FFP mass and nearer FFP distances. I discuss methods for breaking the Refsdal (1966) two-fold degeneracy in ₄,.