He suspects possible scattered light problems. There was strong support for plans to measure the throughput of all the instruments on a regular basis, and making the results available to the APO community. The current plan is to swap out the 1024x1024 chip currently there, and send it back to them for electronics fixing, while we use a 512x512 chip with the resulting smaller field of view. Chris Stubbs and his colleagues at UW have put in a tremendous amount of work to characterize the optics of the telescopes. They are writing a series of reports, which will be distributed widely very soon.
Suspicion weighs most heavily on the secondary.
Chris is planning to build a real Hartman mask, and continue similar tests. He will rule out problems with the figure of the primary by doing the Hartman tests at prime focus. This could conceivably be related to the problems with the secondary drive motors. We discussed the high fraction of engineering time, and how we will know when it is time to slack off. No conclusion was reached.