Interstellar extinction estimates for nearly 90 million stars based on synthetic photometry from Gaia XP spectra

Accurate stellar extinction measurements are essential for recovering intrinsic stellar properties and investigating the three-dimensional distribution of interstellar dust. We present reddening estimates for 87,270,425 stars using synthetic SMSS g r i photometry derived from corrected Gaia DR3 XP spectra, combined with Gaia BP and RP, 2MASS J H K s , and WISE W 1 photometry. Stellar extinction is determined through empirical SED fitting based on reference stellar loci constructed separately for dwarfs and giants. Comparisons with three external extinction catalogs show good overall agreement, with dispersions of 0.049– 0.075 mag in E ( B − V ) . The catalog covers approximately 99.99% of the sky. Using stars with σ d / d < 0.2 , we further construct reddening maps in four distance ranges from 0 to 5 kpc, revealing prominent molecular clouds and large-scale Galactic dust structures. Extinction-corrected color–absolute-magnitude diagrams show significantly tighter stellar sequences and consistent red-clump features in different Galactic fields. The resulting catalog provides a homogeneous data set for stellar extinction correction and studies of Galactic dust structure.