Abstract The scarcity of high-fidelity extinction measurements remains a bottleneck in deriving accurate stellar properties from Gaia parallaxes. In this work, we aim to derive precise extinction estimates for APOGEE DR19 stars, establishing a new benchmark for Galactic stellar population studies. We first determine reddening by comparing observed colors–retrieved from photometric surveys or standardized synthetic magnitudes from Gaia BP/RP spectra–to intrinsic colors predicted via an XGBoost model. The model is trained on minimally reddened stars to infer intrinsic colors and their associated uncertainties, using APOGEE stellar parameters (Teff, log g, Fe/H, and α/Fe). The derived reddening values are then converted into extinctions using an anchor ratio of ABP/ARP = 1.694 ± 0.004, derived from red-clump-like stars. Here, we provide extinction measurements in 39 filters across 10 photometric systems and introduce a new empirical extinction curve optimized for broadband passbands. Our extinction estimates (AV) outperform existing results (Bayestar19, StarHorse, SEDEX), achieving a typical precision of ∼0.03 mag in AV. Notably, we identify systematic deviations of up to 30% between monochromatic and passband-integrated extinction ratios at wavelengths λ 700 nm. This result highlights the necessity of adopting passband-specific coefficients when correcting extinction to derive stellar parameters. The derived extinction and reddening data are available to the community for download through Zenodo.
Yu et al. (Wed,) studied this question.