Physical Sciences and Mathematics Commons^™

Setting Ubvri Photometric Zero-Points Using Sloan Digital Sky Survey Ugriz Magnitudes, Taylor S. Chonis, C. Martin Gaskell

C. Martin Gaskell Publications

We discuss the use of Sloan Digital Sky Survey (SDSS) ugriz point-spread function (PSF) photometry for setting the zero points of UBVRI CCD images. From a comparison with the Landolt (1992, AJ, 104, 340) standards and our own photometry we find that there is a fairly abrupt change in B, V, R, and I zero points around g, r, i ∼ 14.5, and in the U zero point at u ∼ 16. These changes correspond to where there is significant interpolation due to saturation in the SDSS PSF fluxes. There also seems to be another, much smaller systematic effect …