Near Earth Objects - Dynamic Site
NEODyS ∴ Risk page ∴ Notes
Contact »

The following table contains the noteworthy notes about our asteroid impact monitoring system.

2021-Mar-26 The radar observations made in March 2021 of (99942) Apophis have allowed a substantially improved Yarkovsky effect estimate. The current value of the A2 Yarkovsky parameter is (-2.90 +/- 0.25) 10-14 au/d2. As a consequence, all the virtual impactors have been eliminated and this historical asteroid has been removed from the Risk List.
2021-Jan-20 With the apparition of (99942) Apophis of late 2020 - early 2021, new optical observations were available. NEODyS updated the orbit with the determinaton of the A2 Yarkovsky drift to be (-2.84 +/- 0.38) 10-14 au/d2. NEODyS rerun the Impact Monitoring and updated the Impact Risk Table. Due to the already high precision of the orbit determination, NEODyS will update occasionally during this apparition, when the optical and radar detections will provide a significant contribution.
2020-Nov-20 New observations of asteroid (410777) 2009 FD have been submitted on 2020-Nov-16 (MPEC 2020-W27). The updated orbit and the improved Yarkosvky drift estimate ruled out the remaining virtual impactor in 2190. As a consequence, asteroid (410777) 2009 FD have been removed from the Risk List.
2019-Oct-29 We switched to the weighting scheme for asteroid astrometry presented in Veres et al. (2017). We recomputed all the orbits of NEODyS using this new error model and updated the Risk List with the resulting hazard assessment. Note that such a change might affect the hazard assesment results.
2019-Jul-16 We have updated the impactor table of asteroid (410777) 2009 FD. The astrometry collected during the 2019 apparition improved the constraint on the secular semimajor axis drift caused by the Yarkovsky effect and in turn on the trajectory of the asteroid. We adopted a generalisation of the Line Of Variations method in a 7-dimensional space. As a result, the main impact possibility in 2185 is ruled out and the only remaining one is in 2190, but with a very low probability. For further details refer to Del Vigna et al. (2019).
2016-Oct-31 We updated the Risk List after the switch to a different method to sample the Line Of Variations. This new method is described in detail in the paper Del Vigna et al. (2019) and it is uniform in the probability of each sampling interval rather than in the length of each interval, which was the one in use previously. Note that such a change might affect the hazard assesment results.