I learned more about sparse matrix representations today. I mainly learned that there is lots to learn, but I am pretty confident that we astronomers are not using all the technology we should be. I also got fired up about making some astronomy data sets for machine learning, in analogy to the MNIST set of handwritten digits. Many conference participants asked me for data, and I would like to be able to distract some of them towards astronomy problems.
In the afternoon, Lang and I pair-coded SDSS meta-data handling. During this meeting, in the break periods (when normals ski), we implemented the SDSS astrometry meta-data (which is not standards-compliant for historical reasons) and the SDSS photometric calibration meta-data. Soon we will be ready to do some damage on SDSS Stripe 82.