The single best thing today was the first meeting of the new joint group meeting of observational astrophysicists at the brand-spanking-new Simons Center for Computational Astrophysics. In addition to the union of Mike Blanton (NYU), Anthony Pullen (NYU), and my groups, the Director of the Center, David Spergel (SCCA) was there. We had great attendance; introductions alone took more than 90 minutes. Highlights for me included the following: A brief argument broke out about binary stars: Do we really know that both pairs of binaries have the same chemical abundances in detail? Spergel pointed out that the high-velocity stars that Keith Hawkins (Columbia) is finding could have implications for the early universe and the escape fraction of ultraviolet photons. Pullen talked about finding the SZ effect in filaments, Spergel mentioned work on identifying filaments using good machine learning by Shirley Ho (CMU), and MJ Vakili (NYU) talked about the work he has done on halo occupation, which could (in principle) take filament-environment as inputs. Hawkins also talked about a Gaia DR1 zero-day project; Adrian Price-Whelan (Columbia) and I promised to start off next week's group meeting with a visualization of the DR1 data, which at that point will be hours old!
Before and after group meeting, Price-Whelan and I worked on our binary-star (and exoplanet) sampler, building and executing experiments, and writing in the document. One amusing thing is that Megan Bedell (Chicago) gave us some (proprietary) exoplanet radial-velocity data to fit, where she finds one period but thinks there might be more. We found only her one period; confirming her results, but we found that we could get other possible periods if we drop her first data point or blow up her error bars (uncertainties).
One thing that came up in group meeting and I discussed afterwards with Hawkins is the project by Andy Casey (Cambridge), Hawkins, me, and many others to release a reanalysis of the RAVE data that overlap the Gaia DR1 T-GAS sample. Casey and Hawkins have detailed abundances for the red-giant stars, but not the main-sequence stars. I asked Hawkins why the main sequence is so much harder? He stunned me by saying that in fact he thinks the main sequence ought to be easier; we just have red-giant abundances now because people have worked harder on them. There's some medium-hanging (I won't say low-hanging!) fruit right there!