Removal of virtual impactor solutions with precovery data: The case study of 2017 XO2

Abstract We present a search for precovery observations of asteroid 2017 XO 2 , a previously high-rated possible impactor, as an ideal example of how archival searches can be used to clarify, either directly or indirectly, the danger posed by objects whose orbits are poorly known or even lost. In particular, we explore how images which should (but do not) contain the position corresponding to an impacting orbit can provide an indirect way to exclude the impacting solution even in the case of asteroids that are currently lost and therefore not directly observable again.