The ability to do photometry depends directly on the flats matching the sky. SMARTS provides only dome flats by default. After the first month of observatins, good sky flats were obtained, and these revealed that the dome flats only succeed in flattening to 1% the data only for a 2000x2000 region offset from the center (around pixel 1500,1500):
Sky dividied by dome:
Instrumental magnitudes Reduced using Reduced using Dome Flat Sky Flat Sweet spot (1500,1500) 13.888 13.883 Upper right (3500,3200) 13.949 13.888 diferences -0.061mag -0.005mag