At MPIA MW group meeting, Semyeong Oh (Princeton) described her projects to find—and follow up—co-moving stellar pairs and groups in the Gaia TGAS data. She presented the hypothesis test (or model comparison) by showing the two graphical models, which was an extremely informative and compact way to describe the problem. This led to a post-meeting discussion of graphical models and how to learn about them. There is no really good resource for astronomers. We should write one!
I spent the afternoon with Matthias Samland (MPIA) and Jessica Birky (UCSD), debugging code! Samland is adding a new kind of systematics model to his VLT-SPHERE data analysis. Birky is hitting the limitations of some of our code that implements The Cannon. I got a bit discouraged about the latter: The Cannon is a set of ideas, not a software package! That's good, but it means that I don't have a perfectly reliable and extensible software package.