[ ] Compare the Object (coadd) catalog with the truth catalog to calculate purity and completeness for star-galaxy identification as a function of magnitude.
[ ] Compute a variability metric and compare its additional distinguishing power.
May need to include some systematic stochastic intrinsic variability parameter for each of stars and galaxies (AGN?).
[ ] Compute a seeing-weighted variability metric to identify stars vs. galaxies by * how their magnitude changes under different seeing.