Reddening and extinction estimates with APOGEE and Gaia data

The reddening (reddeningAllStarsFinal.csv) and extinction (extinctionsAllStarsFinal.csv) estimates provided below were derived as part of Yu et al. (2026). For comprehensive details regarding the methodology, please refer to the original paper. Data are provided for the following 39 passbands:

If specific reddening values for a color are not directly available in reddeningAllStarsFinal.csv, they can be derived using a linear combination of other available colors. For example, E(B−V) is not listed directly in this catalogue but can be derived from E(B−RP)−E(V−RP) (please find the passband names in the table above). For your convenience, we have provided a python script (explorer.py) to quickly calculate E(B−V) and its associated uncertainty through error propagation. Note on Negative Values: Reddening values may be negative for a small fraction of stars. Users can utilize the associated uncertainties (e.g., 3σ clipping) to manage or remove these negative values.

# ensure both explorer.py and reddeningAllStarsFinal.csv are in the current working directory.
from explorer import get_reddening

# calculate E(B-V) 
df = get_reddening(band1="B", band2="V")

# calculate E(BP-RP) (check the filter names from the table above)
df = get_reddening(band1="gaiabp", band2="gaiarp")

# calculate E(V-J)
df = get_reddening(band1="V", band2="twomassj")

While $E(B-V)$ can be calculated using $A(B)$ and $A(V)$ from extinctionsAllStarsFinal.csv, this approach is less robust than using a linear combination of reddenings in different colors. This is because our process for converting reddening to extinction requires certain assumptions, which may introduce a small uncertainty (at the ~3% level for most stars).

In addition, the table reddeningAllStarsFinal.csv includes the Gaia DR3 source_id , stellar parameters from APOGEE DR19 (reported as weighted averages when multiple entries are available for a given star), distances from Bailer-Jones et al. (2021) based on Gaia EDR3 (r_med_photogeo preferred if available, otherwise r_med_geo), and metadata describing the origin of the colours—either directly obtained from photometric surveys or synthesised from Gaia BP/RP spectra.

For convinience, we also provide table1.csv, which contains the same data as Table 1 in the paper.

Feel free to reach out to Jie Yu (jie.yu@nju.edu.cn),  if you have any questions.