The 64-Trillion-Mile Tape Measure with Dr Jane Clark & David Bennett

David & Jane have been trying to measure the distance to a handful of nearby stars. This requires great precision: the parallax signal is about a quarter of an arc second, or roughly a thirty-thousandth of a degree. It is overwhelmed by atmospheic seeing, the precession of the equinoxes, nutation, aberration and atmospheric refraction. The art is to find out which of these we can remove by using a good coordinate system, which we can neglect over the size of a 0.5° x 1° photo, which ones we can safely average, and which ones we have to correct by calculation. We will report progress on this multi-year project.