Verification of photometric transformations for the LSST minor planet color data

Le résumé fourni par la source

Broadband color photometry of small Solar System bodies provides information about chemical, physical and structural properties of their surface material and helps to group them into different taxonomic classes, which give insights on their origin, physical and dynamical evolution. The recently commenced Vera Rubin Observatory is particularly important is this field of studies, since it has recently started to conduct the Legacy Survey of Space and Time (LSST), which is predicted to dramatically increase the known populations of different types of small Solar System bodies, providing exceptional data on their physical and color properties (Schwamb et al., 2023; Murtagh et al., 2025). The complication is that different observers use different combinations of detectors, filters and telescopes, meaning that the magnitudes of observed objects are derived in different standard photometric systems. The two most widely used photometric systems are the Johnson-Kron-Cousins and the Sloan systems, and the Vera Rubin Observatory implements griz broadband photometric filters similar to the Sloan filters. As the passbands these two systems do not match each other, it may be a problem when we try to compare color measurements of archive data (that have been often collected in the Johnson-Kron-Cousins system in older publications) with new data from the Vera Rubin (obtained in the Sloan system). The usual practice is to apply transformations to convert measurements between the two systems. There are many different transformation relations found in literature, but unfortunately there are no explicit relations for minor planets. The aim of our work was to asses the validity of existing transformations applied on small bodies' color photometric data such as the ones obtained within the LSST survey. For this purpose, we used the archive measurements of Centaurs from different authors, which are ideal test targets for the purpose verification, being divided into two color groups with a wide span of surface colors. The results of the test suggested that the existing transformations may be unreliable for small bodies. To confirm this conclusion, we observed the chosen bright Main-Belt asteroids in both Johnson-Kron-Cousins and Sloan photometric systems using the AGO 70 cm optical telescope located in Modra, Slovakia, and then compared the results obtained from our observations and from different photometric transformations applied on the collected data. In this poster, we will present the results of this comparison, which will be useful for the Vera Rubin users who work with small Solar System bodies.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.