Initial Approach
We are seeking criteria that will permit a relatively uniform all-sky selection of sources unbiased by the vagaries of the Survey itself. To first order, all of the observational variables bear upon the sensitivity/completeness-limit of the observations. Thus uniform selection critera correspond to citing magnitude limits in each band that will yeild completeness a given threshold in the worst case tiles. In reality, users will want more flexible criteria so that they can select regions of the sky with desired completness characteristics.
Sensitivity can be assessed on a tile by tile basis due to the known mapping of background and seeing (i.e. PSP) and instantaneous zeropoint to 10-sigma sensitivity. Previous analysis has established the mapping of the observational variables to absolute sensitivity and generated tile-by-tile all-sky plots of survey performance.
If these 10-sigma limiting magnitudes can, in turn, be scaled with maps of completeness fraction vs. magnitude we can provide all sky maps of 90%, 95%, 99% completeness limit magnitude on a tile-by-tile basis - as well as histograms of sky coverage vs. 90%, 95%, 99% completeness magnitude.
The repeated calibration scans provide the key to assessing completeness fraction vs. magnitude. Previous analysis evaluated overall completness fraction vs. magnitude for the entire set of calibration observations independent of sensitivity.
A similar evaluation, where the calibration dataset is divided according to 10-sigma limiting magnitude, should produce the appropriate scaling relationships. The figure below shows the results of just such a evaluation for the J-band for one of the most commonly observed Northern calibration fields.
