No meteor or fireball had ever been detected before entering
the Earth’s atmosphere before we generated our synthetic population of Earth-impacting asteroids.
6
Then, on 7 October 2008, asteroid 2008 TC3 was discovered by CSS using their 1.5 m telescope.
Rapid followup by other observatories made it almost immediately
clear that the few-meter-diameter (H= 30.7) asteroid would enter
the Earth’s atmosphere within a day and explode over northern Sudan. The substantial and largely self-organized follow-up effort resulted in 789 astrometric observations from amateur and
professional observatories worldwide being submitted to the Minor
Planet Center. Due to the parallax induced by the distance between
the observatories and the proximity of the asteroid, the observations
allowed an accurate pre-impact orbit to be computed despite the
short observational timespan (Table 1). The pre-impact orbit is very
consistent with our predicted impactor orbit distribution as shown
in Fig. 1. Note that, in particular for the eccentricity, the pre-impact
orbit matches the expected impactor population better than the
debiased NEO population or the observed bolide population