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

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

Known NEA population NEANECPHOIEO 05/01/ Size depending on avg. A Known population Bottke model 2001 Rabinowitz model 1994 Stuart model 2004 D>1000m95%73%71% D>100m8,7%3,2% D>10m Known NEO counts versus models

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

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

WFS Idea to search in the close Earth vicinity, wide field vs. low limit. mag. WFS: f=0,15m0,18m 15 °2 14 m 450°/h 30s LINEAR: f=2,2m1,00m 2 °2 20 m 210°/h 5s WFS limitations

Creating model population Models versus known population

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

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. Keplerian motion, 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<14 m a  (mean Earth-Moon distance)

Results Inside Moon orbit

Results Annual size distribution inside Moon orbit

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 asteroid No collides with the Earth

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

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 +18 m & preserving wide field expect rapid number of discoveries in the close Earth vicinity High angular motion is expected Final results

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 +18 m limit magnitude