Lily Zhao (Flatiron) has been looking at the variability of the SDSS-IV BOSS spectrograph calibration frames, in the thought that if we can understand them well enough, we might be able to substantially reduce the observing overheads for the robotic phase of SDSS-V. To start, we are doing simple cross-correlations between calibration images. After all, the dominant calibration changes from exposure to exposure appear to be shifts. But these cross-correlations have weird features in them that I don't understand: In general if you are cross-correlating two images that are very similar, the cross-correlation function should look very symmetric, I think? But Zhao's cross-correlation functions look asymmetric in weird ways. We ended our session puzzled.
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