UnDisLo, day 3

Another impressively productive day just happened in our work bunker on the Central Coast. Conroy (UCSC) came in again, with his student Jieun Choi (UCSC). We discussed ways to generalize "stacking" of spectra in "bins"; it is often (usually?) better to regress. This can be expressed as a wavelength-by-wavelength weighted linear least-square fit. We worked through the linear-regression math in the morning and Choi implemented in the afternoon. The results look sweet. Choi used them to look for consistent residuals in rest-frame (redshifted) and observed-frame (spectrograph) space and it looks like there are effects in both places. At the end of the day, we left Choi with the project of going to quadratic regression.

Marshall (KIPAC) and I worked on extending The Tractor to fit variable point sources, as part of our long-term goal of finding strong gravitational lenses in ground-based data by comparing lens and non-lens explanations of the data. We spent a lot of time understanding inheritance and Lang's pythonisms.

Johnson (UCSC) showed us the results of his Gaussian-Process data-driven calibrations of spectra. They are extremely precise, produce sensible-looking posterior information on spectral properties, and don't seem to erase or interfere with narrow-line issues with the models. We plan to write the method paper this summer.

At the very end of the day, Barclay, Quintana (Ames), and Wolfgang (UCSC) showed up, so I guess we will be talking exoplanets tomorrow! Quintana and Barclay just found the first Earth-radius planet in the habitable zone of a star, and Wolfgang is using physics-based models to fit the radius–period distribution of exoplanets.

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