  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. 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. 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. 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.

Earth and Planetary Astrophysics