Asteroid occultations today and tomorrow: toward the GAIA era

TL;DR

This paper explores how upcoming high-precision asteroid and star data from Gaia will significantly improve the predictability and observation of asteroid occultations, enabling detailed size measurements of smaller asteroids.

Contribution

It models the impact of Gaia-era data on asteroid occultation predictions and demonstrates the potential to measure sizes of asteroids as small as 10 km.

Findings

Future high-accuracy ephemerides will enable occultation observations of much smaller asteroids.

A network of small ground-based telescopes can measure sizes of main belt asteroids down to ~10 km within a few years.

The number of observable occultation events will substantially increase with improved data.

Abstract

Context: Observation of star occultations is a powerful tool to determine shapes and sizes of asteroids. This is key information necessary for studying the evolution of the asteroid belt and to calibrate indirect methods of size determination, such as the models used to analyze thermal infrared observations. Up to now, the observation of asteroid occultations is an activity essentially secured by amateur astronomers equipped with small, portable equipments. However, the accuracy of the available ephemeris prevents accurate predictions of the occultation events for objects smaller than ~100 km. Aims: We investigate current limits in predictability and observability of asteroid occultations, and we study their possible evolution in the future, when high accuracy asteroid orbits and star positions (such as those expected from the mission Gaia of the European Space Agency) will be available. Methods: We use a simple model for asteroid ephemeris uncertainties and numerical algorithms for estimating the limits imposed by the instruments, assuming realistic CCD performances and asteroid size distribution, to estimate the expected occultation rate under different conditions. Results: We show that high accuracy ephemerides which will be available in the future will extend toward much smaller asteroids the possibility of observing asteroid occultations, greatly increasing the number of events and objects involved. A complete set of size measurements down to ~10 km main belt asteroids could be obtained in a few years, provided that a small network of ground-based 1m telescopes are devoted to occultation studies.