•Calibration issues for ZTF (problems and ideas for solutions)
◦What needs to be done during nightly observations, what can be done afterwards?
◦what are the fundamental limits on our (absolute, relative) photometric precision?
◦filter: stability, homogeneity
◦PSF: stability, homogeneity
◦Choice of photometric algorithms
◦Extinction & zero points
◦Strategy: which calibration stars, which filters? Calibration fields?
◦(potential) hardware issues: stray light, ghosting, shutter uniformity
◦flat fielding
◦Forced photometry on difference images vs. source-detected photometry
◦Chip-to-chip subtraction vs sky coverage