**5. Conclusion**

To compute precisely the impact solutions of (99942) Apophis and (144898) 2004 VD17 it is necessary to include small effects like relativistic effects, close approaching asteroids, the Yarkovsky/YORP effect. The use of the software OrbFit is helpful in computing exact possible impacts of asteroids with the Earth. Thanks for the OrbFit Consortium. Also the free software Solex was useful in this work.
