The Light That Catalogues Miss: A Surface-Brightness Completeness Correction for the Optical Background

This paper addresses a specific question in the accounting of the cosmic optical and infrared backgrounds: what fraction of the optical background light is carried by galaxies whose central surface brightness lies below survey detection thresholds, and how large a correction does that impose on counts-based background estimates? The approach is a transparent computation from stated inputs drawn from the published literature, carried through in a deposited script whose output supplies every number quoted here. The principal computed values are: missed light frac lim 26 = 0.0275; missed light frac lim 27 = 0.0149; missed light frac lim 28 = 0.00784; missed light frac lim 29 = 0.00341; correction factor lim 27 = 1.02; correction factor lim 28 = 1.01; missed count frac lim 28 = 0.107. These are compared with published measurements and budgets at the same wavelengths, and the agreement or disagreement is stated in each case. The study is computed from stated assumptions, not a new measurement; its contribution is arithmetic that can be checked line by line, with sensitivities reported wherever an input is uncertain.