The Sloan Digital Sky Survey extended point spread functions

TL;DR

This paper presents an extended and detailed characterization of the SDSS point spread functions, revealing asymmetries and providing tools crucial for low-surface brightness studies in current and future deep imaging surveys.

Contribution

It introduces the first extended PSF models for SDSS, covering 8 arcmin, and demonstrates their application in removing scattered light, aiding low-surface brightness research.

Findings

PSFs extend over 8 arcmin, ten times larger than previous models.

Asymmetries caused by drift scanning mode are identified.

PSF models are publicly available for community use.

Abstract

A robust and extended characterization of the point spread function (PSF) is crucial to extract the photometric information produced by deep imaging surveys. Here, we present the extended PSFs of the Sloan Digital Sky Survey (SDSS), one of the most productive astronomical surveys of all time. By stacking ~1000 images of individual stars with different brightness, we obtain the bidimensional SDSS PSFs extending over 8 arcmin in radius for all the SDSS filters(u, g, r, i, z). This new characterization of the SDSS PSFs is near a factor of 10 larger in extension than previous PSFs characterizations of the same survey. We found asymmetries in the shape of the PSFs caused by the drift scanning observing mode. The flux of the PSFs is larger along the drift scanning direction. Finally, we illustrate with an example how the PSF models can be used to remove the scattered light field produced by the brightest stars in the central region of the Coma cluster field. This particular example shows the huge importance of PSFs in the study of the low-surface brightness Universe, especially with the upcoming of ultradeep surveys, such as the Large Synoptic Survey Telescope (LSST). Following a reproducible science philosophy, we make all the PSF models and the scripts used to do the analysis of this paper publicly available (snapshot v0.5-0-g62d83df).