Asteroid trails in HST images

We report the detection of 1701 new asteroid trails identified in archival HST data via our citizen science project and the subsequent machine learning exploration of the ESA HST science data archive.We detect asteroids to a magnitude of 24.5, which are statistically fainter than the populations of asteroids identified from ground-based surveys. The majority of asteroids are distributed near the ecliptic plane, as expected, where we find an approximate density of 80 asteroids per square degree.

We match 670 trails (39% of the trails found) with 454 known Solar System objects in the Minor Planet Center database, however, no matches are found for 1031 (61%) trails. The unidentified asteroids are faint, being on average 1.6 magnitudes fainter than the asteroids we succeeded to identify. They probably correspond to previously unknown objects.

Citizen science and machine learning are very useful techniques for the systematic search of Solar System objects in existing astronomy science data archives. This work describes a method to find new asteroids in astronomical archives spanning decades in time, which could be effectively applied to other datasets, increasing the overall sample of well characterised small bodies in the Solar System and refining their ephemerides.