Sub-km sized Asteroids Near the Earth & SDSS data Bae Young Ho & Byun Yong Ik Dept. of Astronomy,...
Transcript of Sub-km sized Asteroids Near the Earth & SDSS data Bae Young Ho & Byun Yong Ik Dept. of Astronomy,...
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Sub-km sized Asteroids Near the Earth & SDSS data
Bae Young Ho & Byun Yong IkDept. of Astronomy, Yonsei University
SDSS Korean Scientist Group WorkshopFeb. 20, 2007 YongPyung
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Near-Earth Objects (NEOs)
NECs (Near-Earth Comets) NEAs (Near-Earth Asteroids)
Atens Apollos Amors PHAs (Potentially Hazardous Asteroids)
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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
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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
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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…
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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
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The Number of Detected NEAs
http://neo.jpl.nasa.gov
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Size & Magnitude Distribution of Main Belt Asteroids(2)
F.Yosida et. al., Science, 2004, 33
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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
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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
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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
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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°
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YSTAR-NEOPATSouth Africa Station
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Fast Movers in SDSS data
http://www.sdss.org
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Stereo Observation(1)
Two or more telescopes away from each other
Observing same sky area simultaneously
Measure Parallax / streak on images
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Stereo Observation(2)
Captured by RAPTOR, Fall 2003
Earth
Detection of the Sub-km sized Asteroids near the Earth
A B
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Stereo Observation(3)
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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