1. Arecibo and Goldstone Radar Imaging of Contact Binary Near-Earth Asteroids L. A. M. Benner, M. C. Nolan, J. L. Margot, S. J. Ostro, M. K. Shepard, C. Magri, J. D. Giorgini, and M. W. Busch

2. Outline 1.Overview of NEAs detected by radar 2.Updated binary NEA statistics 3.2005 NB7 4.(1139) Atami 5.Smorgasbord of contact binaries 6.Upcoming NEA radar targets 7.Historical note

3. NEAs Detected by Radar

4. Binary NEAs: Statistics for Radar Targets OVERALL Discovered by radar: 21/33 = 64% Detected by radar25/33 = 76% Discovered at Arecibo:17/33 = 52% (Includes Sisyphus) Discovered at Goldstone:4/33 = 12% Since completion of the upgrade at Arecibo in 1999: Discovered by radar:20/25 = 80% Detected by radar:23/25 = 92% Abundance among radar targets: 17% Arecibo has become the primary technique for discovery and characterization of binary NEAs.

5. Binary NEAs Detected by Radar 2000 DP1072000 2000 UG112000 1999 KW42001, 2002 1998 ST272001, 2004 2002 BM262002 2002 KK82002 Sekhmet2003 1998 RO12003, 2004 2003 SS842003 Hermes2003 1990 OS2003 (1990) Didymos2003 1999 DJ42004 2003 YT12004 2002 CE262004 2005 AB2005 1994 XD2005 Apollo2005 (1980) 2006 GY22006 2004 DC2006 2006 VV22007 2007 DT1032007 2001 SN2632008 2005 NB72008 Sisyphus 1985

6. 2005 NB7

7. (1139) Atami

8. Contact Binary Candidates Detected by Radar 2201 Oljato (?)1983 Jun 4769 Castalia 1989 Aug 2064 Bacchus1996 Mar 4486 Mithra2000 Jul-Aug 2000 YF292001 Jan 2002 FC2002 Jun 2002 NY402002 Aug 1415932002 HK122002 Aug 523871993 OM72003 Jan 683462001 KZ662003 Oct 11066 Sigurd2004 Sep 2005 CR372005 Feb 2004 RF842005 Feb 2004 XL142006 Dec 2007 VD122007 Nov 2007 TU242008 Jan-Feb 2002 TD662008 Feb 4450 Pan2008 Feb Not included: 3908 Nyx 4179Toutatis 25143Itokawa Abundance: ~11% among NEAs > 200 m in diameter

9. What can we estimate for each? ObjectShape? Class OljatoNo S CastaliaAvailable BacchusAvailable Q MithraMaybe 2000 YF29No S 2002 FCNo 2002 NY40MaybeS 2002 HK12MaybeX 1993 OM7No 2001 KZ66YesS SigurdYes S 2005 CR37No C? 2004 RF84No 2004 XL14Not yetCReturns in December 2007 VD12NoS 2007 TU24NoS 2002 TD66NoS PanNoS

10. (2201) Oljato

11. (4769) Castalia

12. (2063) Bacchus

13. (4486) Mithra

14. 2000 YF29

16. 2002 FC

17. 2002 NY40 Arecibo, Aug. 2002

18. (141593) 2002 HK12 Arecibo, Aug. 2002 Aug. 25 Aug. 23

19. (52387) 1993 OM7 Arecibo-Green Bank 2003 Jan 13 2003 Jan 14

20. (68346) 2001 KZ66 Arecibo, Oct. 2003

21. (11066) Sigurd

24. (3908) Nyx

25. 2005 CR37

27. 2004 RF84

28. 2004 XL14

29. 2007 VD12

30. 2007 TU24

32. (4450) Pan Arecibo, Feb. 2008 Feb. 13 Feb. 12Feb. 14

33. Upcoming Radar Opportunities: 55319 1999 JM8May-JuneA 2008 BT18JulyA, G 904032003 YE45JulyA, G 2005 RC34JulyA, G 35107 1991 VHAugustA, G 2000 DP107SeptemberA, G 8567 1996 HW1SeptemberA 1370321998 UO1SeptemberA 1644002005 GN59OctoberA, G 857741998 UT18NovemberA 2004 XL14DecemberA 2008 EV5DecemberA, G 2004 LV3DecemberA 1368491998 CS1JanuaryA, G

34. NEA Radar Detection History 40th anniversary of the 1st asteroid radar detection is in June: 1566 Icarus by Dick Goldstein at Goldstone