Today was the first day of Landolt Standards & 21st Century Photometry in Baton Rouge, organized by Pagnotta (AMNH) and Clayton (LSU). I came to speak about self-calibration. The day started with a historical overview by Bessel (MSSSO), who gave a lovely talk filled with profiles of the many people who contributed to the development of photometric calibration and magnitude systems. Many of the people he talked about (including himself) have filter systems or magnitude systems named after them! Among the many interesting things he touched on was this paper by Johnson, which I have yet to carefully read, but apparently contains some of the philosophy behind standard-star systems. He also discussed the filter choices for the Skymapper project, which seem very considered.
Suntzeff (TAMU) gave an excellent talk about the limitations of the supernova cosmology projects; his main point is that systematic issues with the photometric calibration system are the dominant term in the uncertainty budget. This is important in thinking about where to apportion new resources. He made a great case for understanding physically every part of the photometric measurement system (and that includes the stars, the atmosphere, the telescope, and the detector pixels, among other things). I couldn't agree more!
Grindlay (CfA) blew us away with the scale and content of the DASCH plate-scanning project at Harvard. It is just awesome, in time span, cadence, and sky coverage. Anyone not searching these data is making a mistake! And, as we were recovering from that, Kafka (AAVSO) blew us away again with the scale and scope of the APASS survey, which was designed, built, operated, reduced, and delivered to the public almost entirely by citizen scientists. It is dramatic; we are not worthy!
There were many other great contributions—too many to mention them all—but the day ended with a crawfish boil and then Josh Peek (STScI) and I at the bar discussing recent explosive conversations in the astronomical community around TMT and development in Hawaii.
One last thing I should say: Arlo Landolt (LSU) has had a huge impact on astronomy; his work has enabled countless projects and scientific measurements and discoveries. The development and stewardship of photometric standards and systems, and all the attention to detail it requires, is unglamorous and time-consuming work, ill-suited to most of the community, and yet absolutely essential to everything we do. I can't thank Landolt—and his collaborators and the whole community of photometrists—enough.