The Importance of Having an Extended Point-spread Function in Low Surface-brightness Science

Obtaining and characterizing the extended point-spread function (PSF) is essential to extract accurate photometric information from deep imaging surveys. In this contribution, we present the extended PSFs of the Sloan Digital Sky Survey (SDSS). By stacking images of individual stars with different brightness, two-dimensional SDSS PSFs extending over 8 arcmin in radius for all the SDSS filters have been obtained. We demonstrate how to use the PSF models for correcting the scattered light field produced by the brightest stars in the Coma cluster central region field. This example shows the enormous importance of extended PSFs in the study of the low-surface brightness Universe, especially with the upcoming of ultra-deep surveys such as the Large Synoptic Survey Telescope (LSST). All PSF models and the scripts used to obtain them are publicly available and further details can be found in Infante-Sainz et al. (2020).