Simple look at PS magnitude histograms (Eddie Schlafly)

People were curious during the Aug 11 DRAVG phonecon about estimating PS depth from a simple magnitude histogram, so I whipped one up. Zero points are from SDSS. I've picked one exposure for each filter that had a zero points consistent with the good clusters from zpt_variation_july09. For these exposures, I made a simple histogram of catalog magnitudes + zero points relative to SDSS, enforcing no cuts on the catalog objects. The right panels give the catalog S/N with magnitude, along with the corresponding histogram of S/N.