Woah did we work hard! I didn't have any time to even read email, let alone post. In what follows, recall (or learn) that astrometry.net solves the astrometry for an image blind by the following steps: It uses quads of stars to generate large numbers of hypotheses about pointing, rotation, and scale. It attempts to verify those hypotheses using a likelihood ratio (correct vs random lucky hit). Hopefully one verifies. It then tweaks the verified astrometric WCS to something precise.
On day 2, we worked very hard on tweak; we agreed on a scalar and a algorithm/methodology, and Mierle started hacking. Tweak is probably the biggest gap between where astrometry.net is and where it needs to be with its alpha testers. The functionality for professional and amateur users was discussed, and we came up with some ideas for a more modular system to give users more flexibility. We also made some breakthroughs understanding some false positives (almost none of which are our fault, it turns out) and looked at the awesome assemblage of astrometric
footprints produced by David Warde-Farley. Full-team dinner was delicious.
On day 3, Lang convinced us that he has a much better verify than the current one, and we worked out the math and implementation. Lang implemented. We also talked with Christopher Stumm and Jon Barron about their automatic detection of diffraction spike "false stars" in the USNO-B1.0 catalog and how to evaluate their success using astronomical techniques. A paper about cleaning USNO-B1.0 has begun. Mierle continued to hack. I went home for much-needed sleep!