The errors on zero points obtained by ELIXIR are in general about 0.02 magnitude. To that comes to be added uncertainty on the estimate of the terms of color and airmass.
The total precision noted is thus about 0.03 magnitude. The precise details on the calibration of the CTIO are of the same order of magnitude.
Figure 8.29 shows the discrepancy between the magnitudes of the objects observed for two images taken with the CFHT, we note indeed a dispersion 0.02 magnitude between the two estimates.
We note statistical errors of about 0.07 magnitude on average for the points of photometry of our supernovæ. The error of calibration thus represents in general a marginal contribution to the total photometric error.