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RunQAPhotoThe RunQA table provides information relevant to the average data quality for the objects in each field. This table may be joined to the rest of your query to sub-select only fields of the very highest quality, for instance, with seeing below a certain threshold, if that is desired. If you want just one number that describes the overall quality of a field, your best bet is the fieldQall number (0=bad, 1=acceptable, 2=good, 3=excellent). This overall quality determination is based on the (dereddened) principal colors of all the stars in the field vs. the Galactic value of this quantity, the PSF quality, the difference between Aperture and PSF magnitudes for the same stars in the field, and the seeing.