Gaial4aae: the First Fully-Eclipsing AM CVn

AM CVns are a class of cataclysmic variables consisting of a white dwarf accreting H-deficient matter from a donor star. With periods of 5 to 65 minutes, AM CVns include the shortest period binaries containing white dwarfs. AM CVns are believed to form by one of three formation channels which can in principle be distinguished by the nature of the donor star, but are difficult to constrain observationally. Gaial4aae was one of the first transients discovered by the Gaia Science Alerts project. It eclipses on a period of 50 minutes, and is the only known AM CVn in which the white dwarf is fully eclipsed. This makes it an attractive system for parameter studies. We present an update on our attempts to measure these properties, using highspeed multi-colour photometry. Preliminary results suggest that the donor star is not as degenerate as predicted by models of white dwarf donors.