On Friday, Zaritsky (on sabbatical here at NYU) gave a nice talk on methods for determining the sizes of disks. It turns out, perhaps not surprisingly, that they go out a long way. In discussion at the end, it emerged that the "thin disk" test of CDM merger histories might be made stronger by looking at disks at large radius, since larger radii will be more susceptible to gravitational perturbations, and will also extend further into the substructure-filled dark-matter halo.
Today I did some research on issues with the USNO-B1.0 astrometric catalog. UofT undergrads Stumm and Barron are visiting next week to get a paper drafted on their use of computer vision techniques to improve the catalog. We are finding that a combination of computer vision and astronomical techniques can very reliably clean the catalog of a large subset of the non-real sources (which amount to a couple of percent of the 109 entries in the catalog).