Example of calculating an image zeropoint using bootstrapping with sigma clipping as outlier rejection, where the standard deviation from Chauvenet’s criteria was used. At the top of the panel, we show the image zeropoint and its error, the black line shows the fit using a linear function in the form of f(x)=x+b, the orange points represent the stars that remained after the sigma clipping, and the blue point(s) show rejected stars. The zeropoint is the intercept value from the fit.