Out of the Red: Recalibrating Gaia DR3 for Asteroid Compositional Studies

Understanding the evolutionary paths and physical properties of the asteroid continuum requires large-scale, highly accurate observational data. The Gaia Data Release 3 (DR3) provides an unprecedented statistical dataset, containing visible reflectance spectra in 16 bands for 60,518 Solar System objects. However, a known systematic overestimation of reflectance in the red-photometer (RP) region (wavelengths > 0.55 micron) currently limits its application for accurate taxonomic classification and surface mineralogy.

To bridge this calibration gap and enable the community to robustly investigate the physical and chemical properties of these objects, we present an empirical, per-band multiplicative recalibration of the Gaia DR3 RP spectra. Using a gold-standard subset of 2,395 asteroids distributed across the nine major Bus-DeMeo complexes, we anchor the Gaia spectra to well-established class-mean templates using a class-balanced estimator. We validate this correction against independent ground-based observational surveys and through leave-one-class-out testing across all complexes.

Our combined correction successfully reduces the mean absolute residual against the DeMeo reference by ~51%, dropping from 0.047 to 0.023. This is essential for the study of specific meteorite parent bodies, preserving diagnostic mineralogical band shapes, such as the 1-micron pyroxene-olivine absorption feature characteristic of basaltic V-complex surfaces.

We release the per-band correction factors alongside a fully corrected 16-band catalog of 60,513 asteroids. By resolving the RP instrumental systematic, this recalibrated catalog provides a reliable observational foundation for large-scale statistical and mineralogical investigations into the origins, interrelations, and evolutionary paths of the asteroid population.