Short arc orbit determination and imminent impactors in the Gaia era

¹ Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Boulevard de l’Observatoire, Nice, France
e-mail: fspoto@oca.eu
² IMCCE, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Lille, 77 av. Denfert-Rochereau 75014 Paris, France
³ Dipartimento di Matematica, Università di Pisa, Largo Bruno Pontecorvo 5, Pisa, Italy
⁴ Space Dynamics Services SRL, via Mario Giuntini, Navacchio di Cascina, Pisa, Italy

Received: 14 October 2017
Accepted: 11 January 2018

Abstract

Short-arc orbit determination is crucial when an asteroid is first discovered. In these cases usually the observations are so few that the differential correction procedure may not converge. We developed an initial orbit computation method, based on systematic ranging, which is an orbit determination technique that systematically explores a raster in the topocentric range and range-rate space region inside the admissible region. We obtained a fully rigorous computation of the probability for the asteroid that could impact the Earth within a few days from the discovery without any a priori assumption. We tested our method on the two past impactors, 2008 TC₃ and 2014 AA, on some very well known cases, and on two particular objects observed by the European Space Agency Gaia mission.