Flux fraction and contamination for (left) asteroseismic calibration stars and (right) a larger sample of representative stars spanning a larger range of Kepler magnitudes. The two colors represent the maximum and minimum values observed over all quarters. In general, the flux fraction (the fraction of a star's flux included in the photometric aperture) decreases with increasing magnitude while flux contamination from neighboring stars increases. For the measurement of F₈, we exclude any quarters where the flux fraction is less than 0.9 and/or where the contamination is greater than 0.05. Note the different y-axis scalings between the left and right columns: the photometry for the asteroseismic sample tends to be significantly cleaner than the larger, more representative sample.