GALEX, Gaia, and MCMC

Early in the morning, I met with Dun Wang (NYU), Steven Mohammed (Columbia), and David Schiminovich (Columbia) to discuss our GALEX imaging of the Galactic Plane. We gave Wang and Mohammed tasks of writing titles and abstracts for their papers on the subject. Also, Mohammed showed us his exploration of the GALEXTGAS match, which looks like it is filled with good stuff.

In the afternoon, Dan Foreman-Mackey (UW) and I met to discuss exoplanet results, where Foreman-Mackey has new results on multiplicity based on ABC inference. We followed this with parallel work on our Data Analysis Recipes tutorial on MCMC inference. We re-organized some of the content, reduced scope very slightly, and tried to close issues.

I also worked on posterior samplings for star distances, given parallaxes. I am using Simple Monte Carlo, with two techniques, one that works well for high signal-to-noise parallaxes, and one that works well for low signal-to-noise. The issues are very subtle; a uniform-density prior has a lot of very bad properties in parallax space. I got something working and posted a gif on the twitters.

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