Comparison between calibrated and true magnitudes for the standard stars used to obtain the photometric solution. Each plot shows magnitude residuals vs. true magnitude for different filters for the 4 m data (left) and 0.9 m data (right). Stars classified as outlyers when determining the photometric solution are marked in green. The average standard deviation of the residuals over all filters is  ≈ 0.033 for the 4 m data, and  ≈ 0.03 for the 0.9 m data. A line indicating the zero level residual (black) and the mean of the residual (blue) is also shown (visible only if there is an offset from zero), along with errorbars denoting the average photometric error. The zeropoint correction residuals are consistent with zero across all magnitudes, given the average photometric error. The mean of the residual in the 0.9 m B (upper right) solution is most offset from zero (by 0.024) due to seeing conditions and large photometric error in B. However, the residuals are still within the average photometric error (± 0.032), indicating an accurate calibration is achieved.