Eva Schunova, Robert Jedicke with Peter Veres & Larry Denneau Institute for Astronomy

1. Discovery Process for Finding ARM Candidate Targets Using PanStarrs2 and New Atlas Telescopes. Eva Schunova, Robert Jedicke with Peter Veres& Larry Denneau Institute for Astronomy University of Hawaii at Manoa Target NEO 2 Conference July 9, 2013

2. Purpose • ARM candidate target detection capability with 100% NEO dedicated surveys • PS2 survey (2nd Panoramic Survey Telescope and Rapid Response System) • ATLAS survey (Asteroid Terrestrial-impact Last Alert System) • 3 performance configurations assessed for both: (underperformed: -0.5 mag, nominal, overperformed: +0.5 mag) • Located in Hawaii • Both in development stage

3. Issues • Annual discovery rates of NEOs by PS2 and ATLAS • Follow-up with optical telescopes (IRTF) and radar • ULTIMATE QUESTION: What is the total number of available target candidates in the NEO population? • REQUIRES: • Reliable NEO model • Accurate survey simulations

4. NEO model • Greenstreet et al. (2012) • Based on Bottke et al. (2002) - finer resolution in (a, e, i) • SFD of NEOs according to Brown et al. 2002 • Problem with small size NEO models: • Discoveries are subject to huge selection effects • Large non-gravitational effects (YORP, Yarkovsky )

5. Synthetic ARM candidate targets population • 2.4 x 1011 NEOs generated • 27 < H < 31 • 2m < D < 30m (albedo dependent) • 5 dynamical criteria => Earth-like heliocentric orbits • Survey simulation pre-selection: MOID < Δ(H) • => 7.3 x 106 ARM candidate targets

6. Only 0.003% of model NEOs pass ARM target dynamical & size cuts

7. ATLASAsteroid Terrestrial-impact Last Alert System • Fully automatized => cheap • System operational in 2015 • 1-4 telescopes/ 2 sites • 40 deg2 field-of-view • 80,000 deg2/night • Scans most of the visible night sky 4x/night • Nominal Vlim=20.0 • SELF FOLLOW UP

8. PS22ndPanoramic Survey Telescope and Rapid Response System • 7 deg2field-of-view • ~ 3,600 deg2/night • 1/11th ATLAS coverage • NominalVlim= 22.0 • DetectsNEOs2.5 xfurther away • Visits to the same bore site separated by 3 nights.

9. ATLAS nightly coverage PS2 nightly coverage

10. Survey simulations with MOPS(Moving Object Processing System) Generate NEOs Fulfilling ARM Target Criteria Survey Simulation (ATLAS-N, ATLAS-S, PS2) Implement Weather Losses Implement fill-factor losses Implement trailing losses Determine IRTF and Radar Recovery Availability

11. Total synthetic ARM target discoveries over 2 years with nominal systems

12. Discrepancy between simulations and real data PS1 finds 8x more ARM candidates than predicted!

13. Possible explanations • Imperfect survey simulation • Imperfect NEO model & Size-Frequency distribution • Small NEOs more prone to non-gravitational effects • Unknown dynamical process more efficient in transporting small objects from MB to NEO region • Temporary local NEO density enhancement • (due to tidal disruption, collision, ...)

14. Typical target follow-up window IRTF Arecibo radar window window Little time for characterization after discovery!

15. Typical discoveries of nominal systems ATLAS PS2 >1 NEOs/month Difficult for IRTF follow-up!! (10%) Longer window (~12 days) 50% discoveries observable by radar • >2 NEOs/month • Easier IRTF follow-up (30%) • Short window (~ 4 days) • All discoveries observable by radar

16. Summary • Observed discrepancy between predicted discovery rates and PS1 data - 8 x more real discoveries! • ATLAS and PS2 surveys will discover dozens of ARM candidates per year • Windows for characterization are typically few days (IRTF) and few weeks (radar) • ATLAS has advantages over PS2 for ARM candidate detection • ATLAS: Vlim=20.5 - up to 70 ARM candidates/year FOR HIRE This work was supported by the NASA NEOO grant.

18. Fill factor and trailing losses Courtesy: Denneau et al. 2013

19. Total synthetic ARM target discoveries over 2 years with over-performing systems

20. Annual ARM candidate detections for nominal systems Collectively we will find XXX/year.