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

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

NEAs Detected by Radar

Binary NEAs: Statistics for Radar TargetsOVERALLDiscovered by radar: 21/33 = 64%Detected by radar 25/33 = 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.

Binary NEAs Detected by Radar

2000 DP107 2000

2000 UG11 2000

1999 KW4 2001, 2002

1998 ST272001, 2004

2002 BM26 2002

2002 KK8 2002

Sekhmet 2003

1998 RO1 2003, 2004

2003 SS84 2003

Hermes 2003

1990 OS 2003 (1990)

Didymos 20031999 DJ4 20042003 YT1 20042002 CE26 20042005 AB 20051994 XD 2005Apollo 2005 (1980)2006 GY2 20062004 DC 20062006 VV2 20072007 DT103 20072001 SN263 20082005 NB7 2008

Sisyphus 1985

2005 NB7

(1139) Atami

Contact Binary Candidates Detected by Radar

2201 Oljato (?) 1983 Jun4769 Castalia 1989 Aug2064 Bacchus 1996 Mar4486 Mithra 2000 Jul-Aug

2000 YF29 2001 Jan2002 FC 2002 Jun2002 NY40 2002 Aug

141593 2002 HK12 2002 Aug52387 1993 OM7 2003 Jan68346 2001 KZ66 2003 Oct11066 Sigurd 2004 Sep

2005 CR37 2005 Feb2004 RF84 2005 Feb2004 XL14 2006 Dec2007 VD12 2007 Nov2007 TU24 2008 Jan-Feb2002 TD66 2008 Feb

4450 Pan 2008 Feb

Not included:3908 Nyx4179 Toutatis25143 Itokawa

Abundance: ~11%among NEAs > 200 min diameter

What can we estimate for each?

Object Shape? ClassOljato No SCastalia AvailableBacchus Available QMithra Maybe 2000 YF29 No S2002 FC No 2002 NY40 Maybe S2002 HK12 Maybe X1993 OM7 No 2001 KZ66 Yes SSigurd Yes S2005 CR37 No C?2004 RF84 No 2004 XL14 Not yet C Returns in December2007 VD12 No S2007 TU24 No S2002 TD66 No SPan No S

(2201) Oljato

(4769) Castalia

(2063) Bacchus

(4486) Mithra

2000 YF29

2000 YF29

2002 FC

2002 NY40Arecibo, Aug. 2002

(141593) 2002 HK12Arecibo, Aug. 2002

Aug. 25Aug. 23

(52387) 1993 OM7Arecibo-Green Bank

2003 Jan 13 2003 Jan 14

(68346) 2001 KZ66Arecibo, Oct. 2003

(11066) Sigurd

(11066) Sigurd

(11066) Sigurd

(3908) Nyx

2005 CR37

2005 CR37

2004 RF84

2004 XL14

2007 VD12

2007 TU24

2007 TU24

(4450) PanArecibo, Feb. 2008

Feb. 13

Feb. 12 Feb. 14

Upcoming Radar Opportunities:55319 1999 JM8 May-June A

2008 BT18 July A, G90403 2003 YE45 July A, G

2005 RC34 July A, G35107 1991 VH August A, G

2000 DP107 September A, G8567 1996 HW1 September A137032 1998 UO1 September A164400 2005 GN59 October A, G85774 1998 UT18 November A

2004 XL14 December A2008 EV5 December A, G2004 LV3 December A

136849 1998 CS1 January A, G

NEA Radar Detection History

40th anniversary of the 1st asteroid radar detection is inJune: 1566 Icarus by Dick Goldstein at Goldstone