Ground-based astrometry calibrated by Gaia DR1: new perspectives in asteroid orbit determination
Mignard, F.; Tanga, P.; Altmann, M.; Hestroffer, D.; Barache, C.; Bouquillon, S.; Carlucci, T.; Spoto, F.; Taris, F.; Desmars, J.; Herald, D.; Marchant, J.; Lister, T.
France, Germany, United Kingdom, United States
Abstract
Context. The Gaia Data Release 1 (GDR1) is a first, important step on the path of evolution of astrometric accuracy towards a much improved situation. Although asteroids are not present in GDR1, this intermediate release already impacts asteroid astrometry.
Aims: Our goal is to investigate how the GDR1 can change the approach to a few typical problems, including the determination of orbits from short-arc astrometry, the exploitation of stellar occultations, and the impact risk assessment.
Methods: We employ optimised asteroid orbit determination tools, and study the resulting orbit accuracy and post-fit residuals. For this goal, we use selected ground-based asteroid astrometry, and occultation events observed in the past. All measurements are calibrated by using GDR1 stars.
Results: We show that, by adopting GDR1, very short measurement arcs can already provide interesting orbital solutions, capable of correctly identifying near-Earth asteroids (NEAs) and providing a much more accurate risk rating. We also demonstrate that occultations, previously used to derive asteroid size and shapes, now reach a new level of accuracy at which they can be fruitfully used to obtain astrometry at the level of accuracy of Gaia star positions.