1. 1 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

2. 2 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

3. 3 NASA’s NEO Observation Program (Current Systems) LINEAR MIT/LL Soccoro, NM Catalina Sky Survey UofAZ Arizona & Australia 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/ Pan-STARRS Uof HI Haleakula, Maui NEO-WISE JPL Sun-synch LEO 3 End of Operations Feb 2011, Analysis Of Data Continues

4. 4 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

5. 5 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)

6. 6 2011 MD Nick Howes/Ernesto Guido/Giovanni Sostero/Faulkes Telescope

7. 7 Ecliptic Latitude & Elongation

8. 8 Discovery Magnitudes 8

9. 9 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

10. 10 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

11. 11 Small NEO discoveries by team Prepared by CSS

12. 12 Small NEO discoveries by team Prepared by CSS

13. 13 Monthly Sky Coverage

14. 14 Sky Coverage Fraction

15. 15 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