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Tutorial on Process of Finding Small NEAs Target NEO 2 Open Community Workshop. Timothy Spahr Director, Minor Planet Center Smithsonian Astrophysical Observatory 9 July 2013. Discovery of Small NEOs. --Nearly all “ small NEOs ” found by NASA-funded surveys
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Tutorial on Process of Finding Small NEAs Target NEO 2 Open Community Workshop Timothy Spahr Director, Minor Planet Center Smithsonian Astrophysical Observatory 9 July 2013
Discovery of Small NEOs --Nearly all “small NEOs” found by NASA-funded surveys --Found when close to the Earth (<< 0.1 AU) --Move very rapidly at discovery (several degrees per day) --Streaked/trailed images (hard to detect); nonlinear motion --First discoveries of small objects from Spacewatch team, visual detection in CCD images. Eg, 1991 BA
Catalina Sky Survey UofAZ Arizona & Australia LINEAR MIT/LL Soccoro, NM NASA’s NEO Observation Program(Current Systems) NEO-WISE JPL Sun-synch LEO • Minor Planet Center (MPC) • IAU sanctioned • Int’l observation database • Initial orbit determination • www.cfa.harvard.edu/iau/mpc.html • NEO Program Office @ JPL • Program coordination • Precision orbit determination • Automated SENTRY • http://neo.jpl.nasa.gov/ End of Operations Feb 2011, Analysis Of Data Continues Pan-STARRS Uof HI Haleakula, Maui
Discovery of NEOs—MPC! --All observations of all minor planets and comets made worldwide sent to the Minor Planet Center or MPC --Round-the-clock, year-round operation --Automatic software attempts to identify candidate NEOs and posts on public web page observations, orbit, ephemeris, and uncertainty area --Other observers worldwide attempt to confirm the object
What is a small NEO? A small NEA for us is defined as smaller than ~ 20 meters in diameter (H < 25-26 ish) --Only a few hundred discoveries --Total population of objects < 20 meters in diameter is > 1,000,000 --Very difficult to discover using groundbased optical telescopes (short discovery window) Space-based IR great, but scope must be close to Earth!! (Venus is right out)
2011 MD Nick Howes/Ernesto Guido/Giovanni Sostero/Faulkes Telescope
How to Increase Discovery Rate?? --More sky coverage at fainter magnitudes (this increases volume of space sampled) --note even modest phase angles hamper discovery; GO FAINTER! --Refresh rate is a few days, so repeated coverage essential (6-8 X a month
Discovery Improvement Details --Very important—fainter discovery magnitude = more time we have for physical studies and orbit evaluation!! (see Beeson, Galache & Elvis 2013) --Longer arcs essential for orbit quality --Rotation periods can only be determined by radar or photometry; possible when close to Earth
Small NEO discoveries by team Prepared by CSS
Small NEO discoveries by team Prepared by CSS Prepared by CSS
Conclusions --Dominant player in discovery of small NEOs is the CSS team; get new cameras online quickly for best bang-for-buck and hopefully a good small target! --Wider sky coverage to much fainter magnitudes essential to find more small NEOs; perhaps software improvements --While space-based IR would help, we need meter class instruments and in space NOW to contribute to target search