I spent most of the day reading carefully and commenting on Koposov's paper on modeling the cold GD-1 stream in a (flexible) Milky Way potential. The paper puts some strong constraints (fully marginalized, of course) on Galaxy and gravitational-potential parameters; for some parameters these are the only constraints at this length scale.
I also attended a nice short talk about transit timing by Monika Lendl (MPIA). It turns out that exoplanets that transit their parent stars produce timing sequences that are extremely sensitive to resonant perturbers. A Jupiter-mass transiting exoplanet can produce observable timing residuals when perturbed by even an Earth-mass (or smaller) perturber, if that perturber is interacting resonantly. This is potentially extremely sensitive, but it has the great problem that for a given timing residual pattern, while it may be easy to detect the perturber, it looks very difficult to understand the perturber uniquely.