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Sub-km sized Asteroids Near the Earth & SDSS data

Sub-km sized Asteroids Near the Earth & SDSS data. Bae Young Ho & Byun Yong Ik Dept. of Astronomy, Yonsei University SDSS Korean Scientist Group Workshop Feb. 20, 2007 YongPyung. Near-Earth Objects (NEOs). NECs (Near-Earth Comets) NEAs (Near-Earth Asteroids) Atens Apollos Amors

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Sub-km sized Asteroids Near the Earth & SDSS data

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  1. Sub-km sized Asteroids Near the Earth & SDSS data Bae Young Ho & Byun Yong Ik Dept. of Astronomy, Yonsei University SDSS Korean Scientist Group Workshop Feb. 20, 2007 YongPyung

  2. Near-Earth Objects (NEOs) • NECs (Near-Earth Comets) • NEAs (Near-Earth Asteroids) • Atens • Apollos • Amors • PHAs (Potentially Hazardous Asteroids)

  3. Orbit diagram of NEAs • Aten and Apollo cross Earth’s orbit. • Difficult to observe them with ground based telescopes. • But, potentially very dangerous!!! UK NEO Task Force Report, 2000

  4. Goals of NEO Investigation • Study of dynamics and evolution of the Solar System • Study of statistics and dynamics of near-earth asteroids • Detection & tracking of NEO • Contribution to world-wide effort to protect Earth from NEO impacts

  5. Current NEO Search Programs ;International Effort • Lincoln Near-Earth Asteroid Research (LINEAR) • Near-Earth Asteroid Tracking (NEAT) • Spacewatch • Lowell Observatory Near-Earth Object Search (LONEOS) • YSTAR-NEOPAT • Japanese Spaceguard • etc…

  6. Near-Earth Asteroids • q ≤ 1.3AU, Q ≥ 0.983AU • Potentially Hazardous Asteroids(PHAs) • MOID < 0.05AU ~ 20DL • H < 22 • About 20% of NEAs • NEAs > 3km : completed • NEAs > 1km : about 55% by early 2004 • NEAs less than km-sized : ??? C.R.Chapman, Earth and Planetary Science Letters, 222, 2004

  7. The Number of Detected NEAs http://neo.jpl.nasa.gov

  8. Size & Magnitude Distribution of Main Belt Asteroids(2) F.Yosida et. al., Science, 2004, 33

  9. Sub-km sized Asteroids Near the Earth ; The Characteristics • Most of these are of UNKNOWN nature But, we can guess these are • Very Fast !!! • Streaks (tangential direction) • Large parallax during exposure time (direction of sight → stereo observation) • High (apparent) Brightness

  10. SDSS data & YSTAR-NEOPAT • SDSS data • Sky coverage : 8,000 sq. deg.(DR5) • Single-shot & Multi-band Observation • Detection Streak : More Effective to define orbital elements & velocity & distance • Study of Statistics & Velocity Distribution of Sub-km sized Asteroids around the Earth

  11. SDSS data & YSTAR-NEOPAT • YSTAR-NEOPAT • Stereo Observation • More effective on Detection & Define of Orbital Elements & Velocity & Distance • Automatic Steak Detection Algorithm • Already developed, and presently being tested for SDSS image archive • SDSS Mirror Site

  12. YSTAR-NEOPAT System • Small Optics : 0.5m • Shallow Photometric Depth : 17 R at 5σ • Fast Telescope & Open-Type Enclosure • Very Wide FOV : 1.75°X 1.75°

  13. YSTAR-NEOPATSouth Africa Station

  14. Fast Movers in SDSS data http://www.sdss.org

  15. Stereo Observation(1) • Two or more telescopes away from each other • Observing same sky area simultaneously • Measure Parallax / streak on images

  16. Earth Stereo Observation(2) A B Detection of the Sub-km sized Asteroids near the Earth Captured by RAPTOR, Fall 2003

  17. Stereo Observation(3)

  18. Summary • Characteristics of sub-km sized asteroids near the Earth are UNKNOWN !!! • Massive data of SDSS • Streak Detection → study of statistics & velocity distribution • YSTAR-NEOPAT South African Extension • Dedicated Stereo Observations • More effective to define orbital elements • study of statistics & velocity distribution

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