the best temperature-gravity relationship ever

We have realized that Anna Ho has the most detailed, feature-rich diagram of the temperature–gravity relationship for red giant stars ever created. She has 450,000 red giants from LAMOST labeled with APOGEE and The Cannon. None of these giants is supremely precisely labeled with either temperature or gravity, however, the sheer numbers make for visibility of very subtle features in the diagram that have (perhaps) never been seen before. Anna made visualizations and a gif of the data, and we debated what to do about it all, in the next paper. We are trying to get papers one and two done first.

I performed a code review with Melissa Ness, and we were able to speed up her code by a significant factor. We did it by reducing functionality, of course! But now she can run experiments fast, which is critical in the investigation phase. We made predictions for the figures she should make and what they would look like. She is working on putting far more informative prior beliefs into The Cannon.

Late in the day came the Physics Research Conference (Colloquium). It was by Maria Zuber (MIT), talking about the GRAIL mission to map the geoid of the Moon. The mission was amazingly simple: Two satellites in low orbit around the Moon, sending time-codes to each other and back to Earth. Do the math and figure out the gravitational shape of the Moon. She had many geological (or selenological?) results to discuss. In particular, she has an explanation for the strong morphological differences between the front side and the back side of the Moon. I was impressed that the data analysis was not in the slightest probabilistic: They just did the GPS-like thing (GRAIL is very like a miniature GPS) of finding the best solution to explain the data. It made it clear that a better analysis is possible. Not that I'm volunteering!

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