Estimating the extended PSF, up to several arcminutes, is critical for accurately observing faint structures that provide key insights into galaxy evolution. These include comprehensive galaxy counts, radial profiles, truncations, color distribution, sky measurements, halo shapes, tidal features, dwarf galaxies, the circumgalactic medium (CGM), and intracluster light (ICL). Moreover, an extended PSF can significantly increase the effective survey area. For instance, in deep imaging by the Hyper Suprime-Cam (HSC) on the 8.2-meter Subaru Telescope, up to 20% of the survey area can be lost due to masking near bright stars.

A team led by Sepideh Eskandarlou, under the supervision of Mohammad Akhlaghi at CEFCA, addressed this challenge using the J-PLUS survey as a reference. The J-PLUS project, which aims to cover 8,500 square degrees of sky visible from the Javalambre Astrophysical Observatory, employs non-parametric PSFs extending to a radius of 40 arcminutes for individual exposures. The team developed an optimized pipeline to automatically subtract the extended PSF from each exposure, balancing runtime efficiency and storage requirements. This approach can be applied to other large surveys, such as J-PAS, offering a scalable solution for PSF subtraction. The research also documents variations in PSFs between exposures based on CCD position and filter type.

This work was presented at the symposium "Deciphering the Low Surface Brightness Universe," which focused on handling low-surface-brightness structures. Sepideh Eskandarlou’s research, titled "Characterization and Automatic Subtraction of the Extended PSF in J-PLUS," was part of this specialized forum coordinated by researcher Helena Domínguez. Over 20 CEFCA researchers participated in this significant scientific event.