Megan Bedell (Chicago) and Dan Foreman-Mackey (UW) came into town for a few days of hacking on stellar spectra. We had long discussions about the point and scope of our project, and made plans for the week. Foreman-Mackey argued that we should switch over to a Gaussian-Process model for the stellar spectrum. That seems sensible, in part because he has the fastest code in the world for that. He didn't object to our “fit and subtract” approach to looking for stellar variability in the spectral domain: As Andrew Gelman (Columbia) teaches us, inspecting residuals is how you make choices for model extension, improvement, and elaboration.
After lunch, Maryam Modjaz (NYU) gave a great, wide-ranging talk about her work on supernovae, supernova progenitors, chemical abundances, and the supernova–GRB connection. As I have commented here before, I think her results—which show that broad-line type-2c supernovae with and without associated gamma-ray burst live in different kinds of environments puts strong pressure on any model of GRB beaming. I also learned in her talk that there are new classes of transients that are brighter than classical novae and fainter than supernovae that are currently unexplained.