The high-quality astrometry of Gaia offers unique opportunities for solar system science. Apart from the astrometry of ~150,000 asteroid at ~1 mas accuracy expected in DR3, an additional way of collecting ultra-precise asteroid astrometry can be devised, based on the utilization of the extremely precise positions and parallaxes of stars (~20 μas, for mag<15) in the Gaia catalog.
Stars are often occulted by asteroids, which cast a moving ‘shadow’ path upon the Earth, with cross-track width equal to their diameters. Combining the immense accuracy of Gaia stellar data with precision timing of predicted occultations, one can deduce asteroid positions with an accuracy well below the Gaia nominal ~1 mas!
Occultation astrometry can be a game-changer for asteroid astrometry, extending the time-coverage of Gaia. In the pre-Gaia era the only prediction with a reasonable reliability concerned, in general, asteroids several tens of km in size. This limit is brought down to a few km thanks to Gaia astrometry. A single site, that before could hope in a few positive events per year, can target several 10s per month (mag<14 stars; good for ~40 cm telescopes). We use different telescopes for our observations, ranging from portable instruments to the 1 m C2PU telescopes at Plateau de Calern (OCA). We are also implementing a project of continuous monitoring at the universCity robotic 0.5 m telescope, under construction at that same site.
- L. Abe
- M. Conjat
- J. Ferreira
- E. Lagadec
- M. N'Diaye
- R. Leiva
- L. Liberato
- J.P. Rivet
- P. Tanga
- D. Vernet
- M. Buie (SWRI, CO, USA)
- S. Bouquillon (SYRTE, France)
- F. Colas (IMCCE, Paris)
- J. Desmars (IMCCE, France)
- K. Tsiganis (University of Tessalonica, Greece)
- P. Machado (University of Lisbon, Portugal)
- B. Sicardy (LESIA, Paris)
- F. Spoto (Minor Planet Center, MA, USA)
- D. Souami (NAXIS, Belgium)
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