Phase coloring of asteroids: Detection limits for survey photometry

The asteroid phase coloring effect manifests as variations in spectral slopes, color indices, albedo, and absorption band depths as a function of phase angle. To date, the effect has been observed in a limited number of asteroids through spacecraft and ground-based observations, though laboratory meteorite measurements, and sparse photometric survey data (e.g., ATLAS, SDSS).

In this study, we evaluate the detectability and reliability of phase coloring detection using sparse photometric data from several large-scale surveys (ATLAS, ZTF, SDSS, LSST, Euclid, and VISTA). We simulate survey spectral slopes based on laboratory meteorite spectra and survey-specific filter sets to estimate the expected magnitude of the coloring effect for various meteorite types and surveys.

By simulating uncertainties in color indices and phase curve parameters, we define detection thresholds for the expected slope variations. Our analysis shows that detecting phase coloring requires stringent constraints on both color uncertainties and phase curve fits. Using actual survey data, we assess whether reliable detections of phase coloring are currently achievable, and for which subset of observed asteroids. These results provide a quantitative framework for interpreting the subtle coloring effect and for optimizing future observational strategies.