The apertures are pixel number, not side dimensions of a pixel array. The total aperture is the number of pixels recorded and delivered for each target. The optimal aperture are those pixels designated as source pixels for light curve construction within the automated data processing pipeline. The pixel numbers provided are not a strict rule. The exact aperture size for each source depends on CCD module and is optimized on a map of targets before each quarter, so the table provides averaged guidelines by target magnitude. This relationship may be adjusted as the mission matures. Currently, the total GO program is limited to 3,000 x 32 = 96,000 long cadence pixels and 25 x 85 = 2,125 short cadence pixels each month. This pixel limit supercedes the target limit of 3,000 long cadence targets and 25 short cadence targets. Potentially a large number of bright sources can curtail the target list before the target limit has been reached. Note that GO proposals are not limited to the source magnitudes within this table. GOs may propose for sources brighter and fainter than the examples tabulated here, which span only the range of the exoplanet program targets.

There will be occassion when GOs must override the Kepler magnitudes within the KIC or provide Kepler magnitudes for sources not found within the KIC. For extended sources, non-standard observations of point sources, or sources displaying large-amplitude variability revealing significant deviations from the Kepler magnitude stored within the KIC, proposers must provide an alternative Kepler magnitude and flag each occurance of this within the comments column of their target table. For example, the brightest magnitude should be provided for highly-variable targets. For GO sources with no KIC counterpart, proposers will work with the GO Office to define custom apertures for upload to the spacecraft. In each case, proposers must choose and justify quoted magnitudes and aperture sizes carefully within the scientific/technical section of their proposal, so that the cycle peer review panel and the Kepler Science Office are convinced that the program is budgeting pixels efficiently. Poorly chosen magnitudes or custom apertures will affect proposal grades and PIs are encouraged to contact the before proposal submission if they reqiure aperture endorsement or issue clarification.