Improved background subtraction for the Sloan Digital Sky Survey images

Understand

We describe a procedure for background subtracting Sloan Digital Sky Survey (SDSS) imaging that improves the resulting detection and photometry of large galaxies on the sky.

• Within each SDSS drift scan run, we mask out detected sources and then fit a smooth function to the variation of the sky background.
• This procedure has been applied to all SDSS-III Data Release 8 images, and the results are available as part of that data set.
• We have tested the effect of our background subtraction on the photometry of large galaxies by inserting fake galaxies into the raw pixels, reanalyzing the data, and measuring them after background subtraction.