Peter Vereš, Juraj T óth, Leonard Kornoš

1. Peter Vereš, Juraj Tóth, Leonard Kornoš Search for very close approaching NEAs Comenius University, Bratislava, Slovakia Faculty of mathematics, physics and informatics Department of astronomy, physics of the Earth and meteorology

2. Objectives • Create NEA model population • Simulation of geometrical conditions during close Earth encounters • Detection probability of synthetic population

3. Known NEA population • Known NEO counts versus models

4. Known NEA population • Orbital elements & size distribution of NEA • Smaller NEAs – lesser count • Closest approaches to the Earth within Moon orbit distance & their size distribution

5. Survey programs Limiting conditions: Apparent magnitude Absolute magnitude – Albedo - Size Our work: 18m – 1km albedo vs. diameter 23m – 100m 28m – 10m

6. WFS • Idea to search in the close Earth vicinity, wide field vs. low limit. mag. WFS: f=0,15m 0,18m 15°2 14m 450°/h 30s LINEAR: f=2,2m 1,00m 2°2 20m 210°/h 5s WFS limitations

7. Creating model population Models versus known population

8. Random number generation according to distributions a, e, i, H Creating model population NEO space correction Angular elements – random seed N bodies – each contains 6 orbital elements, size (H) Generation accuracy 10 964 780synthetic bodies

9. Numerical integration Numerical integrator (Montebruck-Pfleger) JPL database DE406 (accuracy +3000years =~25m in planets orbits) Multistep backward integration of Adams-Bashforth-Moulton type Perturbing elements vs. Keplerianmotion, 12-grade of accuracy Reduction: only Sun & Earth perturbing Input (name, MJD, a, e, i,, , v, H) Output (name, MJD, , R, h, Ph, RA, DC ) Integration time 1 year Output conditions: V<14m a (mean Earth-Moon distance)

10. Results Inside Moon orbit

11. Results Annual size distribution inside Moon orbit

12. Results reduction for WFS • Possible discoveries for H>19 bodies + visual mag. condition = 18 discoveries • For H>19, >0,46AU,, angular velocity limiting magnitude correction for WFS, site of observation – declination restriction, obs. time restriction = 3,6 – 5,4 discoveries • Analyzing each encounter as real (real time and date, RA & DA, time spent inside search area ) = 3,35 discoveries • Synthetic asteroidNo. 2 961 437 collides with the Earth

13. Results reduction for WFS Apparent movement of 18 simulated bodies, their orbit type & sizes

14. Final results • 80 NEA inside Moon orbit annually • 18 NEA are capable to find under ideal conditions annually with WFS • 3 NEA are easily to find with WFS Modra annually • Optimistic models expect up to 120 discoveries with WFS • Limiting magnitude +18m & preserving wide field expect rapid number of discoveries in the close Earth vicinity • High angular motion is expected

15. Future • Actual & accurate models • Higher number of integrated orbits – bodies down to bolid size (1 meter) • Longer integration time – fluctuations and orbits perturbation due to close encounters • Build of WFS, discoveries & confirmation of our model and other models • Upgraded survey system with +18m limit magnitude

16. Let's find them!