Vera C. Rubin LSST synthetic magnitudes derived from Gaia XP spectra
- 1Ruđer Bošković Institute
Abstract
Context. In the context of Milky Way studies, the Vera C. Rubin Observatory’s Legacy Survey of Space and Time is often described as a deep extension of the Gaia survey. In the future, joint analyses of the Gaia and LSST data promise to bring new insights into the Galaxy’s structure and formation history. However, the relatively small overlap in the magnitude ranges of the two surveys raises the question of how to perform a joint calibration of these datasets. Aims. We produce high-quality synthetic LSST photometry from Gaia XP low-resolution spectra and use SDSS and DES observed photometry to calibrate the spectra. Methods. We developed a method for empirically correcting Gaia XP spectra using SDSS Stripe 82 photometry. We projected sources for which Gaia XP data are available onto a magnitude–magnitude grid and calculated the residuals between uncorrected synthetic and observed SDSS magnitudes, which we then used to derive correction coefficients across spectral regions corresponding to each photometric band. Results. The correction significantly reduces systematic trends and scatter in the synthetic magnitudes: the median residuals decrease by an order of magnitude (e.g. for the u band the improvement is from 0.038 to 0.002 mag), and the standard deviation of residuals typically reduces by factor of 2 (e.g. for the u band from 0.2 to 0.07 mag). Conclusions. Our correction approach improves the reliability of synthetic photometry derived from Gaia XP spectra and enables a joint analysis of Gaia and LSST data for studies of Galactic structure and stellar populations.
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BibTeX
@article{oleksandra2026vera,
title = {{Vera C. Rubin LSST synthetic magnitudes derived from Gaia XP spectra}},
author = {Razim Oleksandra and Tisanić Krešimir and Palaversa Lovro},
journal = {Astronomy \& Astrophysics},
year = {2026},
month = oct,
doi = {10.1051/0004-6361/202555722},
url = {https://doi.org/10.1051/0004-6361/202555722},
note = {CC BY},
}
RIS
TY - JOUR
TI - Vera C. Rubin LSST synthetic magnitudes derived from Gaia XP spectra
AU - Razim Oleksandra
AU - Tisanić Krešimir
AU - Palaversa Lovro
PY - 2026
DA - 2026/10/24
JO - Astronomy & Astrophysics
DO - 10.1051/0004-6361/202555722
UR - https://doi.org/10.1051/0004-6361/202555722
AB - Context. In the context of Milky Way studies, the Vera C. Rubin Observatory’s Legacy Survey of Space and Time is often described as a deep extension of the Gaia survey. In the future, joint analyses of the Gaia and LSST data promise to bring new insights into the Galaxy’s structure and formation history. However, the relatively small overlap in the magnitude ranges of the two surveys raises the question of how to perform a joint calibration of these datasets. Aims. We produce high-quality synthetic LSST photometry from Gaia XP low-resolution spectra and use SDSS and DES observed photometry to calibrate the spectra. Methods. We developed a method for empirically correcting Gaia XP spectra using SDSS Stripe 82 photometry. We projected sources for which Gaia XP data are available onto a magnitude–magnitude grid and calculated the residuals between uncorrected synthetic and observed SDSS magnitudes, which we then used to derive correction coefficients across spectral regions corresponding to each photometric band. Results. The correction significantly reduces systematic trends and scatter in the synthetic magnitudes: the median residuals decrease by an order of magnitude (e.g. for the u band the improvement is from 0.038 to 0.002 mag), and the standard deviation of residuals typically reduces by factor of 2 (e.g. for the u band from 0.2 to 0.07 mag). Conclusions. Our correction approach improves the reliability of synthetic photometry derived from Gaia XP spectra and enables a joint analysis of Gaia and LSST data for studies of Galactic structure and stellar populations.
SN - 0004-6361
SN - 1432-0746
ER -