Near-Earth Asteroid Surface Roughness Depends on Compositional Class


L. A. M. Benner, S. J. Ostro, C. Magri, M. C. Nolan, E. S Howell, Jon D. Giorgini,
J. L. Margot, M. W. Busch, M. K. Shepard, P. A. Taylor, and R. F. Jurgens

Abstract
Radar observations of 214 near-Earth asteroids (NEAs) reveal a very strong correlation 
of circular polarization ratio with visible-infrared taxonomic class, establishing 
distinct differences in the centimeter-to-several-decimeter structural complexity of 
objects in different spectral classes.  The correlation may be due to intrinsic 
mechanical properties of different mineralogical assemblages but also may reflect
very different formation ages and collisional histories.  The highest ratios are
measured for groups associated with achondrittic igneous rocky meteorites: the E class,
whose parent body may be 3103 Eger, and the V class, derived from the mainbelt 
asteroid (and Dawn mission target) 4 Vesta.

Submitted to Icarus: February 2008
Revised:             June 2008

Last update: 2012 Aug 06

http://echo.jpl.nasa.gov/~lance/scoc/scoc.html

The paper is available from Icarus at:

http://dx.doi.org/10.1016/j.icarus.2008.06.010

and was published in Icarus 198, 294-304 (2008).


OBJECTS NOT INCLUDED IN THE PUBLISHED PAPER:

                                      Taxonomic 
  Asteroid          H (mag)  Class    Reference
  4581 Asclepius    20.4             
  5143 Heracles     14.0      O
  8567 1996 HW1     15.3      S       M. D. Hicks, pers. comm., E.S. Howell, pers. comm., Birlan et al. 2009 (BAAS 41, 1061-1062)
 35107 1991 VH      16.7      S       Binzel et al. 2004, De Leon et al. 2010
 54660 2000 UJ1     17.6      S       M. D. Hicks and K. J. Lawrence, pers. comm.
 66146 1998 TU3     14.7    
 68216 2001 CV26    16.2      S       V. Reddy, pers. comm. 
                              R       Ye 2011  (AJ 141)
 85989 1999 JD6     16.9      K       Binzel et al. 2001, Icarus 151, 139-149.
                              K       De Leon et al. 2010
                              Xk, S   M. D. Hicks, pers. comm.
 90403 2003 YE45    17.5      S       M. D. Hicks, pers. comm. 
 96590 1998 XB      16.1      S       
                              V       M. D. Hicks and K. J. Lawrence, pers. comm.
100926 1998 MQ      16.7      S       Whitely 2001, Bus et al. 2002, Binzel et al. 2004
136617 1994 CC      17.7      Sq      M. D. Hicks et al., pers. comm.
136849 1998 CS1     17.7      Sq      M. D. Hicks et al., pers. comm.
137032 1998 UO1     16.6      Sq      M. D. Hicks, pers. comm.
138525 2000 OJ8     16.4      Sr
141018 2001 WC47    18.6      S       M. D. Hicks and K. J. Lawrence, pers. comm.
143651 2003 QO104   15.9      S       M. D. Hicks, pers. comm.
                              R       Ye 2011
144411 2004 EW9     16.5      
152664 1998 FW4     19.5      C       M. D. Hicks, pers. comm.
153814 2001 WN5     18.3      Xc      M. D. Hicks, pers. comm.
153958 2002 AM31    18.2      V       M. D. Hicks, pers. comm.
                              Sq      E. S. Howell, pers. comm.
154029 2002 CY46    16.3      S       M. D. Hicks, E. S. Howell, pers. comm.
159402 1999 AP10    16.4      L       M. D. Hicks, S. C. Lowry, and P. R. Weissman, pers. comm.
                              S       Ye 2011
162421 2000 ET70    18.1      X       
                              CE      M. D. Hicks and K. J. Lawrence, pers. comm.
164400 2005 GN59    17.4      Sq      M. D. Hicks, pers. comm.
                              S       E. S. Howell, pers. comm.
170502 2003 WM7     17.1       
175706 1996 FG3     18.0      C
192642 1999 RD32    16.3      C       M. D. Hicks and K. J. Lawrence, pers. comm.
207398 2006 AS2     20.3      S       M. D. Hicks, pers. comm.
208023 1999 AQ10    20.3      S       Binzel et al. (2004)
                              K       M. D. Hicks et al., pers. comm.
217796 2000 TO64    16.7      Sq      M. D. Hicks and K. J. Lawrence, pers. comm.
217807 2000 XK44    17.7      S       M. D. Hicks and K. J. Lawrence, pers. comm.
277475 2005 WK4     20.7    
297300 1998 SC15    19.2
297418 2000 SP43    18.5      
308242 2005 GO21    16.4      
326290 1998 HE3     21.7      R       Fevig and Fink (2007)
                              V       Hicks and Lawrence, pers. comm.
326732 2003 HB6     17.5
329614 2003 KU2     17.7
       1994 NK      19.9
       1998 SC15    19.2              
       2000 CO101   18.9      Xk      Binzel et al. 2004
       2001 CQ36    22.7
       2001 FE90    20.0      A  (S?) M. D. Hicks et al., pers. comm.
       2001 SZ269   19.3      Sq ?    M. D. Hicks and K. J. Lawrence, pers. comm.
       2001 WC47    18.6      Sl      M. D. Hicks and K. J. Lawrence, pers. comm.
       2002 BF25    22.3      
       2002 QC7     19.9      
       2003 AK18    19.6       
       2003 FH      19.0      
       2003 UV11    19.3      Xk      M. D. Hicks, T. Trong, pers. comm.
                              S       E. S. Howell, pers. comm.
       2003 WH166   21.9      
       2004 FG11    20.9
       2004 LV3     18.6      V       M. D. Hicks, pers. comm.
       2005 GC120   19.6      V       M. D. Hicks, K. J. Lawrence, pers. comm.
       2005 RC34    19.5      E       V. Reddy and J. Emery, pers. comm; E. S. Howell, pers. comm., M. D. Hicks, pers. comm.
       2005 YU55    21.9      C       M. D. Hicks and K. J. Lawrence, pers. comm.
       2006 AL8     18.3
       2006 CF      20.5
       2006 CJ      20.1 
       2007 LE      19.2      C       M. D. Hicks, pers. comm.
       2007 RU17    18.1      O       M. D. Hicks and K. J. Lawrence, pers. comm.
       2007 XB10    17.4              
       2008 BT18    18.2      V       V. Reddy and J. Emery, pers. comm.
       2008 EE5     19.1      Sl      M. D. Hicks et al., pers. comm.
       2008 EV5     20.0      C       M. D. Hicks, K. J. Lawrence, B. J. Buratti pers. comm.
                              X       V. Reddy, pers. comm., Ye 2011
       2008 QS11    19.8      Xc      M. D. Hicks, pers. comm.
       2008 QY      18.6      Xk      M. D. Hicks and K. J. Lawrence, pers. comm
       2008 SV11    18.2      CX      M. D. Hicks, pers. comm.
       2008 UE7     20.4      
       2008 YT30    19.3 
       2009 AV      17.9
       2009 DO111   22.8      
       2009 DR3     21.5      S       M. D. Hicks, pers. comm.
       2009 KC3     18.1      C       E. S. Howell, pers. comm.
       2009 UN3     17.7      S       M. D. Hicks, T. Barajas, J. Shitanishi, pers. comm.
       2009 WV25    24.0    
       2010 AL30    27.0
       2010 AF40    25.0
       2010 DJ1     26.8      
       2010 GU21    21.1
       2010 KX7     21.8      Sa      M. D. Hicks and K. J. Lawrence, pers. comm.
       2010 JL33    17.6      T       M. D. Hicks, K. J. Lawrence, pers. comm
       2010 JN71    21.4
       2010 SV3     20.7
       2010 TU149   20.6
       2010 UM7     27.6
       2010 UP      24.5
       2011 CP4     21.2              SC/OC > 1.0
       2011 EZ78    17.2      S       M. D. Hicks, K. J. Lawrence, and B. J. Buratti, pers. comm.
       2011 LC19    18.5     dark
       2011 SE97    24.7
       2011 SQ12    20.8
       2011 UB      27.5
       2011 UK21    25.1
       2011 WN2     25.2
       2011 WS74    23.9
       2011 WS95    24.9
       2011 XD1     23.9
       2011 YH40    23.0
       2012 BD14    26.7
       2012 BT23    19.0
       2012 BX34    27.6
       2012 DH4     20.7
       2012 DH54    27.6
       2012 DW60    26.5
       2012 DX      27.6
       2012 DX13    23.9
       2012 EO8     24.4
       2012 FZ23    18.2
       2012 HL      22.6
       2012 HM      24.1
       2012 HM8     23.9
       2012 LZ1     19.8
       2012 MM11    20.2
       2012 MU2     20.7
       2012 MY2     26.3
       2012 OO      20.5
       2012 OQ      21.8

N = 112

Of the targets in the list above, E. Howell, R. Vervack et al. have IRTF data 
for 1998 UO1, 1999 AP10, 2001 FE90, 2003 QO104, and 2008 SV11.
Their spectral classes will be added above when they become available.

Binzel et al. also have IRTF spectra of 2008 SV11.


UPCOMING NEA TARGETS 
Proposed and/or scheduled for radar observations at Arecibo and Goldstone through March, 2013:

                              H    Spectral Taxonomic                Previous radar
     Asteroid      Date      (mag) Class    Reference                detection? 
153958 2002 AM31   2012 Jul  18.1   V  M.D. Hicks, pers. comm.         No
                                    Sq E. S. Howell, pers. comm.
  4581 Asclepius   2012 Aug
162421 2000 ET70   2012 Aug                                            Yes: Feb. 2012
  4769 Castalia    2012 Sep         S                                  Yes: 1989
  2063 Bacchus     2012 Sep         Q                                  Yes: 1996
136993 1998 ST49   2012 Oct  
214869 2007 PA8    2012 Oct 
       1999 SF10   2012 Oct
       1994 XD     2012 Nov                                            Yes: 2005
163899 2003 SD220  2012 Nov       
  4179 Toutatis    2012 Dec                                            Yes: 1992, 1996, 2000, 2004, 2008
       2006 VB14   2012 Dec
 33342 1998 WT24   2012 Dec                                            Yes: 2001
       2010 BB     2012 Dec
203471 2002 AU4    2012 Dec
       2002 AY1    2013 Jan                                            Yes: 2002
 52762 1998 MT24   2013 Jan
 99942 Apophis     2013 Jan                                            Yes: 2005, 2005, 2006
137199 1999 KX4    2013 Jan
       2012 DA14   2013 Feb
  3752 Camillo     2013 Feb
       2008 DG17   2013 Feb
  7888 1993 UC     2013 Mar
       2007 EO88   2013 Mar
       2002 TR190  2013 Mar
  4034 Vishnu      2013 Mar                                            Yes: 1989



Table 1: Ordered list

Last update: 2012 Mar 20

                              Spectral
  Asteroid           H (mag)  Class   SC/OC +-     P (h)
  ========           =======  ======  =====        =====
   433 Eros            11.2    S      0.28  0.06     5.27             Binzel et al. 2004, De Leon et al. 2010
  1036 Ganymed          9.5    S      0.18  0.06    10.31             Binzel et al. 2004, De Leon et al. 2010
  1566 Icarus          16.9    Q      0.5   0.2      2.273            Tholen 1989, Hicks et al. 1998
  1580 Betulia         14.5    C      0.20  0.03     6.13             Tholen 1989, Rivkin et al. 2005
  1620 Geographos      15.6    S      0.20  0.01     5.223            Binzel et al. 2004
  1627 Ivar            13.2    S      0.21  0.01     4.797            Binzel et al. 2004, Davies et al. 2007, De Leon et al. 2010
  1685 Toro            14.2    S      0.15  0.05    10.196            Binzel et al. 2004
  1862 Apollo          16.3    Q      0.33  0.01     3.066  BINARY    Binzel et al. 2004, De Leon et al. 2010
  1866 Sisyphus        13.0    S      0.32  0.04     2.4    BINARY    Binzel et al. 2004, De Leon et al. 2010
  1915 Quetzalcoatl    19.0    S      0.27  0.08     4.9              Tholen 1989
  1917 Cuyo            13.9    S      0.21  0.03     2.69             Binzel et al. 2004
  1981 Midas           15.5    V      0.65  0.13     5.22             Binzel et al. 2004
  2062 Aten            16.8    S      0.39  0.06    40.77             Binzel et al. 2004
  2063 Bacchus         17.1    Q      0.21  0.01    14.9              Binzel et al. 2004
  2100 Ra-Shalom       16.1    K      0.25  0.04    19.797            Shepard et al. 2008
  2101 Adonis          18.7           1.02  0.11    
  2201 Oljato          15.3    S      0.31  0.02    26.               Binzel et al. 2004
  3103 Eger            15.4    E      0.92  0.06     5.706            Gaffey et al. 1992, Binzel et al. 2004
  3199 Nefertiti       14.8    S      0.47  0.04     3.021            Binzel et al. 2004
                               A                                      De Leon et al. 2010.  Added 2010 Sep 14
  3200 Phaethon        14.6    B      0.25  0.02     3.604            Binzel et al. 2004
  3757 1982 XB         19.0    S      0.27  0.05     9.005            Tholen 1989
  3908 Nyx             17.4    V      0.75  0.03     4.426            Cruikshank et al. 1991, Binzel et al. 2004, De Leon et al. 2010
  4034 1986 PA         18.1    O      0.21  0.14                      Binzel et al. 2004
  4179 Toutatis        15.3    S      0.29  0.01   130    NPA         Binzel et al. 2004, Davies et al. 2007, De Leon et al. 2010
  4183 Cuno            14.4    S      0.32  0.02     3.56             Binzel et al. 2004
  4197 1982 TA         14.6    S      0.25  0.02     3.538            Binzel et al. 2004
  4450 Pan             17.2    S      0.23  0.03   slow               M. D. Hicks, pers. comm.
  4486 Mithra          15.6    S      0.48  0.01    67.5              M. D. Hicks et al., pers. comm., Added 2010 Feb. 18
  4544 Xanthus         17.1    S      0.07  0.12                      Binzel et al. 2010, Added 2010 Jan 21
  4660 Nereus          18.2    E      0.74  0.08    15.1              Delbo et al. 2003, Binzel et al. 2004
  4769 Castalia        16.9           0.30  0.02     4.095
  4953 1990 MU         14.1    Q      0.36  0.03    14.218            Hicks et al. 1998
  5189 1990 UQ         17.3           0.37  0.05    
  5381 Sekhmet         16.5    V      0.52  0.02    ~3       BINARY   Davies et al. 2007
  5604 1992 FE         16.4    V      0.52  0.06     6.026            Binzel et al. 2004
                               VQXR                                   Ye 2011
  5660 1974 MA         15.7    Q      0.37  0.15    17.5              Binzel et al. 2004, De Leon et al. 2010
  6037 1988 EG         18.7    S      0.32  0.02     2.76             Fevig and Fink 2007
  6178 1986 DA         15.1    M      0.09  0.02     3.58             Ostro et al. 1991
  6239 Minos           17.9    S      0.23  0.04     3.556            Binzel et al. 2010, Added 2010 Jan 21 
  6489 Golevka         19.2    Q      0.23  0.02     6.026            Binzel et al. 2004, Davies et al. 2007
  7025 1993 QA         18.0           0.28  0.03     2.506            
  7335 1989 JA         17.0           0.19  0.06     
  7341 1991 VK         16.7    Q      0.17  0.02     4.21             Binzel et al. 2004, De Leon et al. 2010
  7482 1994 PC1        16.8    S      0.27  0.04     2.6              Binzel et al. 2004
  7753 1988 XB         18.6    B      0.18  0.02                      Binzel et al. 2004
  7822 1991 CS         17.4    S      0.28  0.01     2.389            Binzel et al. 2004
  7889 1994 LX         15.3    V      0.57  0.05     2.741            Binzel et al. 2004
  8014 1990 MF         18.7           0.19  0.04     
  8201 1994 AH2        16.3    O    >> no SC/OC <<  23.949            REFERENCE?
  9856 1991 EE         17.4    S      0.24  0.02     3.045            Harris et al. 1998
 10115 1992 SK         17.0    S      0.34  0.05     7.32             Binzel et al. 2004
 11066 Sigurd          15.2    S      0.30  0.03     8.496            Binzel et al. 2004
 11500 Tomaiyowit      18.4    S      0.37  0.03    73.               Binzel et al. 2004   (1989 UR)
 12711 Tukmit          16.0    S      0.27  0.05     3.484            Binzel et al. 2004   (1991 BB)
 13651 1997 BR         17.6    S      0.16  0.04    33.644            Binzel et al. 2004
 14827 Hypnos          18.2    C?     0.26  0.02                      Ostro et al. 1989
 16834 1997 WU22       15.4    S      0.20  0.10     9.345            Binzel et al. 2004
 17511 1992 QN         16.9    X      1.10  0.19     5.99             Binzel et al. 2004
 22753 1998 WT         17.4    S      0.25  0.03                      Whitely 2001, Lazzarin et al. 2005
 22771 1999 CU3        16.7    S      0.28  0.02     3.782            Binzel et al. 2004
 23187 2000 PN9        15.9    S      0.24  0.02     2.53             I. N. Belskaya, pers. comm.
 25143 Itokawa         19.0    S      0.27  0.04    12.132            Binzel et al. 2004, Davies et al. 2007, De Leon et al. 2010
 26663 2000 XK47       18.0           0.24  0.02    
 29075 1950 DA         16.8    M      0.14  0.03     2.122            Rivkin et al. 2005
                               K                                      Hicks and Lawrence, pers. comm.
 30825 1990 TG1        14.7    S      0.27  0.03     2.624            F. DeMeo and R. P. Binzel, pers. comm., De Leon et al. 2010
 33342 1998 WT24       17.9    E      0.97  0.10     3.697            Lazzarin et al. 2004
 35396 1997 XF11       16.9    X      0.20  0.02     3.26             Binzel et al. 2004
                               E                                      De Leon et al. 2010, added 2010 Sep. 14
 37655 Illapa          17.7    C      0.20  0.04     2.66             M. D. Hicks, pers. comm.
 38071 1999 GU3        19.4    XC     0.36  0.07   216                F. De Meo, pers. comm, added 2011 Jun 10
 52387 1993 OM7        17.4           0.27  0.02     
 52760 1998 ML14       17.6    S      0.30  0.03    14.98             Davies et al. 2007
 53319 1999 JM8        15.0    P      0.19  0.01   168   NPA          Benner et al. 2002, Binzel et al. 2004
 54509 YORP            22.6    S      0.21  0.02     0.288            REFERENCE?
 65803 Didymos         18.0    M      0.20  0.02            BINARY    Binzel et al. 2004, Kitazato et al. 2004, Pravec et al. 2006
                               S                                      De Leon et al. 2006, Added 2009 Sep. 
                               Xk                                     De Leon et al. 2010, Added 2010 Sep. 14
 65909 1998 FH12       19.1           0.16  0.03    ~3
 66063 1998 RO1        18.0    S      0.24  0.05     2.5    BINARY    Abell et al. 2005
 66391 1999 KW4        16.5    S      0.45  0.11     2.765  BINARY A  Binzel et al. 2004, Davies et al. 2004
                                      0.45  0.20    18      BINARY B  
 68346 2001 KZ66       16.5    S      0.22  0.02                      Lazzarin et al. 2005, De Leon et al. 2010
 68950 2002 QF15       16.2    S      0.23  0.02    29                F. DeMeo and R. P. Binzel, pers. comm., De Leon et al. 2010
 69230 Hermes          17.5    S      0.19  0.02    13.89   BINARY    Rivkin et al. 2004
 85182 1991 AQ         17.1           0.22  0.03    
 85774 1998 UT18       19.1    C      0.25  0.01   ~34                Binzel et al. 2004
 85938 1999 DJ4        18.5    Q      0.19  0.02     2.51   BINARY    Binzel et al. 2004
 87024 2000 JS66       18.6    X      0.73  0.08                      Lazzarin et al. 2005
 89136 2001 US16       20.2           0.39  0.05    12.4  NPA
 99942 Apophis         19.7    Q      0.1   0.2     30.6              Binzel et al. 2006
100085 1992 UY4        17.6    P      0.20  0.02    12.9              Volquardsen et al. 2007
101955 1999 RQ36       20.8    B      0.18  0.01     4.29             Delbo et al. 2003
136770 1996 PC1        20.3           0.22  0.02    
137924 2000 BD19       17.1    V     >> NO CW DATA <<                 V. Reddy, PDS entry, added 2011 May 02
138127 2000 EE14       16.9    S     >> no SC/OC   <<                 M. D. Hicks, pers. comm.
138175 2000 EE104      20.1    XC     1.1   0.3                       F. De Meo, pers. comm., added 2011 Jun 10
138258 2000 GD2        19.1    S      0.32  0.15                      Binzel et al. 2004
138971 2001 CB21       18.4           0.20  0.02     3.302
141432 2002 CQ11       19.9           0.12  0.02     
141593 2002 HK12       18.1    X      1.09  0.06    12.69             E. S. Howell, pers. comm.
144900 2004 VG64       18.2    S      0.25  0.02                      F. DeMeo and R. P. Binzel, pers. comm.
144901 2004 WG1        17.4           0.17  0.01
152560 1991 BN         19.0    Q      0.27  0.04                      Binzel et al. 2004
152770 1999 RR28       18.3    E      0.9   0.1     ~17   NPA?        E. S. Howell, pers. comm.
153591 2001 SN263      16.9    P      0.16  0.01    fast     TRIPLE   R. P. Binzel, pers. comm. 
154275 2002 SR41       20.2           >> CW DATA IS BAD <<
154276 2002 SY50       17.6           0.44  0.08     4.823
162000 1990 OS         19.3           0.23  0.03             BINARY
162039 1996 JG         19.1           0.19  0.04     
162181 1999 LF6        18.2    S      0.25  0.01    48?               M. D. Hicks and T. Barajas, pers. comm., Added 2009 Nov 01
                                                                      Binzel et al. 2010, Added 2010 Jan 21
162416 2000 EH26       21.3           0.23  0.07     
163295 2002 HW         19.3           0.0   0.1
163692 2003 CY18       18.0           0.20  0.05
163732 2003 KP2        15.3    C      0.26  0.08   151                De Meo and Binzel 2007
164121 2003 YT1        16.2    V      0.61  0.06     2.34    BINARY   Abell et al. 2005
                               S                                      E. S. Howell, pers. comm. Added 2009 Oct.
164211 2004 JA27       19.3    Q      0.20  0.04                      F. DeMeo and R. P. Binzel, pers. comm.
179806 2002 TD66       19.9    S      0.26  0.02                      REFERENCE?
185851 2000 DP107      18.0    X      0.25  0.02     2.7755 BINARY    Yang et al. 2003, Pravec et al. 2006
230111 2001 BE10       19.1    S      0.19  0.02     4.194            Binzel et al. 2010, Added 2010 Jan 21
                               S                                      De Leon et al. 2010, Added 2010 Sep 14
                               R                                      Ye 2011
234145 2000 EW70       21.1    F      0.15  0.09                      Whiteley 2001
       1989 AZ         19.4           0.13  0.04
       1994 XD         19.1           0.21  0.05             BINARY
       1998 BY7        21.4           0.35  0.04    
       1998 KY26       25.5    C      0.5   0.1      0.178            Ostro et al. 1999
       1998 ST27       19.5    C      0.30  0.01     3.1     BINARY   Abell et al. 2005
       1999 FN19       22.4    S      0.22  0.05     3.5?             Binzel et al. 2004
       1999 FN53       18.4           0.19  0.07     
       1999 MN         21.4    Sq     0.21  0.05                      Hicks et al. 2010, Added 2010 Jun 15
       1999 NW2        23.1           0.35  0.03     
       1999 TN13       23.6           >> No SC/OC <<
       1999 TY2        23.3    S      0.34  0.15     0.121            REFERENCE?
       2000 CE59       20.2    L      0.24  0.02     
       2000 ED14       20.7           0.28  0.12
       2000 LF3        21.6           0.19  0.02     
       2000 QW7        19.4    Q      0.22  0.03    71.3              Binzel et al. 2010, Added 2010 Jan 21
       2000 RD53       19.9           0.21  0.05    14.96
       2000 UG11       20.3    S      0.22  0.11     4.44   BINARY    Kitazato et al. 2004
       2000 UK11       25.0           0.38  0.05     0.266
       2000 YA         23.7    S      0.16  0.02     0.666            Binzel et al. 2004
       2000 YF29       20.2    S      0.23  0.01                      Binzel et al. 2004
       2001 AV43       24.4           0.01  0.10     0.17
       2001 BF10       22.3           0.27  0.03     
       2001 CP36       23.7           0.91  0.02     
       2001 EB18       19.1           0.23  0.05     
       2001 EC16       22.2           0.23  0.08     
       2001 FR85       24.5           0.17  0.01     
       2001 GQ2        20.0           0.27  0.06     
       2001 JV1        21.3    S      >> NO CW DATA <<                REFERENCE?
       2001 SE286      17.1           0.26  0.01     9.323 
       2001 SG276      17.7           0.18  0.03     
       2001 SP263      25.6           0.16  0.02     
       2001 UP         25.7           0.09  0.01     
       2001 WM15       25.0           0.83  0.02     
       2001 XX4        22.0           0.15  0.03     
       2001 YE4        20.5           0.61  0.11     
       2001 YP3        21.9           0.17  0.03     
       2002 AA29       24.1           0.26  0.07     
       2002 AL14       17.7    L      0.20  0.01     2.31             Binzel et al. 2004, De Leon et al. 2010
       2002 AV         20.7    K      0.10  0.01                      Binzel et al. 2004
       2002 AY1        20.6           0.21  0.02     
       2002 BG25       20.8           0.20  0.02     
       2002 BM26       20.0    P      0.20  0.03     2.7    BINARY    Delbo et al. 2003, Binzel et al. 2004
       2002 CE26       16.8    C      0.21  0.02     3.293  BINARY    Shepard et al. 2006
       2002 FC         18.8           0.35  0.08     
       2002 FD6        22.2           0.27  0.03     
       2002 KK8        20.5           0.50  0.05            BINARY
       2002 NY40       19.2    S      0.33  0.07    19.982            Rivkin et al. 2003
       2002 TD60       19.2    S      0.41  0.10     2.851            Lazzarin et al. 2005, De Leon et al. 2010
       2002 TS69       24.5           0.16  0.02     
       2002 TZ66       25.9           0.0   0.2      
       2002 VE68       20.3           1.0   0.2     13.5
       2003 EP4        23.7           0.29  0.04     
       2003 GY         20.0           1.11  0.15
       2003 HM         21.7           0.19  0.04    
       2003 HN16       22.0           0.41  0.04    
       2003 MS2        21.0           0.28  0.02     
       2003 QB30       26.4           0.37  0.02
       2003 RU11       25.6           0.25  0.02
       2003 SR84       25.2           >> NO SC ECHOES <<  2.34
       2003 SS84       21.8           0.72  0.05  BINARY
       2003 TH2        22.8           1.48  0.4 
       2003 TL4        19.4           0.30  0.03     27.4
       2003 UC20       18.1    C      0.21  0.03                      Abe et al. 2007
       2004 AD         24.5           0.45  0.15
       2004 DC         18.0           0.9   0.05  BINARY
       2004 FY31       21.9           0.09  0.03
       2004 HX53       23.3           0.13  0.05
       2004 RF84       18.2           0.10  0.01
       2004 RQ10       20.9           0.31  0.15
       2004 VB         20.7           0.16  0.05
       2004 VW14       19.4           0.37  0.05
       2004 XL14       21.2    C      0.49  0.01                      F. DeMeo and R. P. Binzel, pers. comm.
       2004 XP14       19.5    E      0.9   0.05                      Reddy et al. 2006
       2005 AB         17.5    C      0.15  0.04     3.34  BINARY     Kumar et al. 2006, De Meo and Binzel 2007
       2005 CR37       18.9    C?     0.32  0.03     6.49             Benner et al. 2006
       2005 ED318      20.7    Q      0.36  0.02                      F. DeMeo and R. P. Binzel, pers. comm.
       2005 EK70       17.4           0.15  0.07
       2005 EU2        23.1           0.26  0.06  
       2005 FA         25.2           0.45  0.08
       2005 HB4        24.3           0.05  0.15
       2005 JE46       17.8           0.38  0.01
       2005 NB7        18.7    S      0.24  0.01                      M. D. Hicks, pers. comm.
       2005 OE3        20.3           0.38  0.03
       2005 TD49       26.4           0.15  0.10
       2005 TF49       19.1           0.73  0.06
       2005 TU50       21.3           1.02  0.15
       2005 WA1        21.5           0.28  0.10
       2005 WC1        20.6           1.12  0.02     2.5?
       2005 WJ56       18.1    E      0.92  0.15     days             M. D. Hicks, pers. comm. V. Reddy, pers. comm.
       2005 WK56       22.5           0.90  0.10
       2005 XA         26.3           0.06  0.08
       2006 AM4        21.8    Q      0.27  0.08     0.085            M. D. Hicks, pers. comm.
       2006 BQ6        19.7    C      0.33  0.03     4.41             M. D. Hicks, pers. comm.
       2006 GY2        18.7           0.21  0.02  BINARY
       2006 QV89       25.3           0.0   0.25
       2006 RH120      29.6           0.58  0.03     0.0458
       2006 RZ         20.3    B      0.55  0.05     4.9              F. DeMeo and R. P. Binzel, pers. comm.
       2006 UQ17       21.9           0.20  0.06
       2006 VV2        16.8    S      0.27  0.02     2.43  BINARY     V. Reddy, pers. comm., Binzel et al. 2010
       2006 WB         22.8           0.38  0.03
       2007 DT103      19.2    S      0.40  0.05  BINARY              Hicks and Somers 2007, Binzel et al. 2010
       2007 EH         27.6         >> no SC/OC <<
       2007 FY20       24.8           0.15  0.10
       2007 TU24       20.2    S      0.37  0.01                      M. D. Hicks, pers. comm.
       2007 VD12       20.0    S      0.27  0.05     7.43             M. D. Hicks, pers. comm.
       2007 XH16       19.6           0.38  0.01

N = 214 (counting both components of 1999 KW4 as one object)

Completeness: 214/218 = 0.986

1994 AH2, 1999 TN13, 2000 BD19, 2000 EE14, 2001 JV1, 2002 SR41, 2003 SR84, and 2007 EH are excluded 
because SC/OC is not available.

We have spectral types for: 113/214 = 52.8% of the reduced sample  (published in the paper)
Other spectral classes have been added since the paper was published and are indicated in bold.

Summary
-------
Reduced        214
Not available    8 
               ---
Total          222



Table 2: Ranked list

Last update: 2010 Feb 18

SC/OC for objects observed at both Arecibo and Goldstone have
been averaged (indicated by "A & G").  Ratios reported for objects 
observed at Goldstone are indicated by "G" and for objects observed at
Arecibo by "A."  

Rank    Object            H    Type  SC/OC +/-   Obs.  Notes            Reference
----    ------            -    ----  ----- ---   ----  -----            ---------
             2003 TH2     22.8       1.48  0.4   A
             2005 WC1     20.6       1.12  0.02  G                      
             2003 GY      20.0       1.11  0.15  A
       17511 1992 QN      16.9  X    1.10  0.19  G                      Benner et al. 1997
      138175 2000 EE104   20.1       1.1   0.3   A                      Howell et al. 2001
      141593 2002 HK12    18.1  X    1.09  0.06  A
        2101 Adonis       18.7       1.02  0.11  A                      Benner et al. 1997
             2005 TU50    21.3       1.02  0.15  A
             2002 VE68    20.3       1.0   0.2   G
       33342 1998 WT24    17.9  E    0.97  0.10  A G                    Busch et al. 2008
        3103 Eger         15.4  E    0.92  0.06  A G 1986, 1991, 1996   Benner et al. 1997
             2005 WJ56    18.1  E    0.92  0.15  A G
             2001 CP36    23.7       0.91  0.02  A
      152770 1999 RR28    18.3  E    0.9   0.1   A G                    
             2004 DC      18.0       0.9   0.05  A G         BINARY     Taylor et al. 2006, 2008
             2004 XP14    19.5  E    0.9   0.05  G                      Benner et al. 2006 
             2005 WK56    22.5       0.90  0.10  A
             2001 WM15    25.0       0.83  0.02  A
        3908 Nyx          17.4  V    0.75  0.03  A G                    Benner et al. 2002b
        4660 Nereus       18.2  E    0.74  0.08  A                      Brozovic et al. 2009
       87024 2000 JS66    18.6  X    0.73  0.08  A
             2005 TF49    19.0       0.73  0.06  A
             2003 SS84    21.8       0.72  0.05  G A         BINARY
        1981 Midas        15.5  V    0.65  0.13  A G 1987               Ostro et al. 1991b
      164121 2003 YT1     16.2  V    0.61  0.06  A
                                S              
             2001 YE4     20.5       0.61  0.11  A
             2006 RH120   29.6       0.58  0.03  G
        7889 1994 LX      15.3  V    0.57  0.05  A                      
             2006 RZ      20.3  B    0.55  0.05  G
        5381 Sekhmet      16.5  V    0.52  0.02  A           BINARY     
        5604 1992 FE      16.4  V    0.52  0.06  G A
        1566 Icarus       16.9  Q    0.5   0.2   G    1996              Mahapatra et al. 1999
             1998 KY26    25.5  C    0.5   0.1   G                      Ostro et al. 1999b
             2002 KK8     20.5       0.50  0.05  A   
             2004 XL14    21.2  C    0.49  0.01  G
        4486 Mithra       15.6  S    0.48  0.01  G 
        3199 Nefertiti    14.8  S    0.47  0.04  A                      Shepard et al. 2004
       66391 1999 KW4 a   16.5  S    0.45  0.11  G A  2001   BINARY     Ostro et al. 2006
       66391 1999 KW4 b         S    0.45  0.20  G A  2001   BINARY     Ostro et al. 2006
             2004 AD      24.5       0.45  0.15  A
             2005 FA      25.2       0.45  0.08  A 
      154276 2002 SY50    17.6       0.44  0.08  G
             2002 TD60    19.2  S    0.41  0.10  A
             2003 HN16    22.0       0.41  0.04  A
             2007 DT103   19.2  S    0.40  0.05  G           BINARY
        2062 Aten         16.8  S    0.39  0.06  G                      Benner et al. 1997
       89136 2001 US16    20.2       0.39  0.05  G
             2000 UK11    25.0       0.38  0.05  G
             2005 JE46    17.8       0.38  0.01  G
             2005 OE3     20.3       0.38  0.03  G
             2006 WB      22.8       0.38  0.03  A
             2007 XH16    19.7       0.38  0.01  A
        5189 1990 UQ      17.3       0.37  0.05  G
        5660 1974 MA      15.7  Q    0.37  0.15  A
       11500 Tomaiyowit   18.4  S    0.37  0.03  G  (1989 UR)
             2003 QB30    26.4       0.37  0.02  A
             2004 VW14    19.4       0.37  0.05  A
             2007 TU24    20.2  S    0.37  0.01  G
        4953 1990 MU      14.1  Q    0.36  0.03  G
       38071 1999 GU3     19.4       0.36  0.07  G    1999              Pravec et al. 2000
             2005 ED318   20.7  Q    0.36  0.02  G
             1998 BY7     21.4       0.35  0.04  G
             1999 NW2     23.1       0.35  0.03  G
             2002 FC      18.8       0.35  0.08  G
       10115 1992 SK      17.0  S    0.34  0.05  G                      Busch et al. 2006
             1999 TY2     23.3  S    0.34  0.15  A
        1862 Apollo       16.3  Q    0.33  0.01  A     1980  BINARY     Ostro et al. 1991b
             2002 NY40    19.2  S    0.33  0.07  A
             2006 BQ6     19.7  C?   0.33  0.03  G
        1866 Sisyphus     13.0  S    0.32  0.04  A                      Ostro et al. 1991b
        4183 Cuno         14.4  S    0.32  0.02  A
        6037 1988 EG      18.7  S    0.32  0.02  G
      138257 2000 GD2     19.1  S    0.32  0.15  G
             2005 CR37    18.9  C?   0.32  0.03  A                      Benner et al. 2006
        2201 Oljato       15.3  S    0.31  0.02  A                      Ostro et al. 1991b
             2004 RQ10    20.9       0.31  0.15  A
        4769 Castalia     16.9       0.30  0.02  A G                    Ostro et al. 1991b
       11066 Sigurd       15.2  S    0.30  0.03  A
       52760 1998 ML14    17.6  S    0.30  0.03  G A                    Ostro et al. 2001
             1998 ST27    19.5  C    0.30  0.01  A           BINARY     Benner et al., in prep.
             2003 TL4     19.4       0.30  0.03  G
        4179 Toutatis     15.3  S    0.29  0.01  G     1996             Ostro et al. 1999a
             2003 EP4     23.7       0.29  0.04  A     
         433 Eros         11.2  S    0.28  0.06  G A 1975 & 1988        Magri et al. 2001
        7025 1993 QA      18.0       0.28  0.03  G
        7822 1991 CS      17.4  S    0.28  0.01  G                      Benner et al. 1999a
       22771 1999 CU3     16.7  S    0.28  0.02  A     2003
             2000 ED14    20.7       0.28  0.12  A
             2003 MS2     21.0       0.28  0.02  G
             2005 WA1     21.6       0.28  0.10  A
        1915 Quetzalcoatl 19.0  S    0.27  0.08  A                      Shepard et al. 2004
        3757 1982 XB      19.0  S    0.27  0.05  A                      Shepard et al. 2004
        7482 1994 PC1     16.8  S    0.27  0.04  G
       12711 Tukmit       16.0  S    0.27  0.05  A   (1991 BB)
       25143 Itokawa      19.0  S    0.27  0.04  A     2001             Ostro et al. 2004
       30825 1990 TG1     14.6  S    0.27  0.03  A
       52387 1993 OM7     17.4       0.27  0.02  A
      152560 1991 BN      19.0  Q    0.27  0.04  A
             2001 BF10    22.3       0.27  0.03  A
             2001 GQ2     20.0       0.27  0.06  A
             2002 FD6     22.2       0.27  0.03  G             
             2006 AM4     21.8       0.27  0.02  A
             2006 VV2     16.8  S    0.27  0.02  A
             2007 VD12    20.0  S    0.27  0.05  G
       14827 Hypnos       18.2  C?   0.26  0.02  G                      Ostro et al. 1989
      163732 2003 KP2     15.3  C    0.26  0.08  A
      179806 2002 TD66    19.9  S    0.26  0.02  A
             2001 SE286   17.1       0.26  0.01  A
             2002 AA29    24.1       0.26  0.07  A                      Ostro et al. 2003
             2005 EU2     23.1       0.26  0.06  A G
        2100 Ra-Shalom    16.1  K    0.25  0.04  A 1981,1984,2000,2003  Shepard et al. 2000, 2007
        3200 Phaethon     14.6  B    0.25  0.02  A
        4197 1982 TA      14.6  S    0.25  0.02  G
       22753 1998 WT      17.4  S    0.25  0.03  G     2005
       85774 1998 UT18    19.1  C    0.25  0.01  A
      144900 2004 VG64    18.2  S    0.25  0.02  A  
      162181 1999 LF6     18.2  S    0.25  0.01  A
      185851 2000 DP107   18.0  X    0.25  0.02  G            BINARY
             2003 RU11    25.6       0.25  0.02  A
        9856 1991 EE      17.4  S    0.24  0.02  A
       66063 1998 RO1     18.0  S    0.24  0.05  A     2003   BINARY
       23187 2000 PN9     15.9  S    0.24  0.02  A     2001
       26663 2000 XK47    18.0       0.24  0.02  A
             2000 CE59    20.2       0.24  0.02  A
             2005 NB7     18.7  S    0.24  0.01  A
        4450 Pan          17.2  S    0.23  0.03  A
        6239 Minos        17.9  S    0.23  0.04  G
        6489 Golevka      19.2  Q    0.23  0.02  G     1995             Hudson et al. 2000
       68950 2002 QF15    16.2  S    0.23  0.02  A     2003
      162000 1990 OS      19.3       0.23  0.03  A     1990   BINARY    Ostro et al. 1991b
      162416 2000 EH26    21.3       0.23  0.07  A
             2000 YF29    20.2  S    0.23  0.01  A 
             2001 EB18    19.1       0.23  0.05  A
             2001 EC16    22.2       0.23  0.08  G
       68346 2001 KZ66    16.5  S    0.22  0.02  A
       85182 1991 AQ      17.1       0.22  0.03  A
      136770 1996 PC1     20.3       0.22  0.02  A
             1999 FN19    22.4  S    0.22  0.05  G
             2000 QW7     19.4  S    0.22  0.03  G
             2000 UG11    20.3  S    0.22  0.11  G            BINARY
        1627 Ivar         13.2  S    0.21  0.01  A                      Ostro et al. 1990
        1917 Cuyo         13.9  S    0.21  0.03  A G                    Ostro et al. 1991b
        2063 Bacchus      17.1  Q    0.21  0.01  G                      Benner et al. 1999b
        4034 1986 PA      18.1  O    0.21  0.14  A                      Shepard et al. 2004
       54509 YORP         22.6  S    0.21  0.02  G A                    Taylor et al. 2007
             1994 XD      19.1       0.21  0.05  A            BINARY
             1999 MN      21.4  Sq   0.21  0.05  A  2005
             2000 RD53    19.9       0.21  0.05  G
             2002 AY1     20.6       0.21  0.02  A
             2002 CE26    16.8  C    0.21  0.02  A            BINARY    Shepard et al. 2006
             2003 UC20    18.1  C    0.21  0.03  A
             2006 GY2     18.7       0.21  0.02  G            BINARY
        1580 Betulia      14.5  C    0.20  0.03  A G 2002               Magri et al. 2007
        1620 Geographos   15.6  S    0.20  0.01  A G 1983 & 1994        Ostro et al. 1996
       16834 1997 WU22    15.4  S    0.20  0.10  A
       35396 1997 XF11    16.9  X    0.20  0.02  G
       37655 Illapa       17.7  C    0.20  0.04  G
       65803 Didymos      18.0  M S  0.20  0.02  G            BINARY
      100085 1992 UY4     17.6  P    0.20  0.02  G A                    Benner et al., in prep.
      138971 2001 CB21    18.4       0.20  0.02  A
      163692 2003 CY18    18.0       0.20  0.05  A
      164211 2004 JA27    19.5  Q    0.20  0.04  A
             2002 AL14    17.7  L    0.20  0.01  A
             2002 BG25    20.8       0.20  0.02  A
             2002 BM26    20.0  P    0.20  0.03  A
             2006 UQ17    21.9       0.20  0.06  A
        7335 1989 JA      17.0       0.19  0.06  A G                    Mahapatra et al. 2002
        8014 1990 MF      18.7       0.19  0.04  A                      Ostro et al. 1991b
       53319 1999 JM8     15.0  P    0.19  0.01  G A                    Benner et al. 2002a
       69230 Hermes       17.5  S    0.19  0.02  G            BINARY
       85938 1999 DJ4     18.5  Q    0.19  0.02  A            BINARY
      162039 1996 JG      19.1       0.19  0.04  G
             1999 FN53    18.4       0.19  0.07  G
             2000 LF3     21.6       0.19  0.02  A
      230111 2001 BE10    19.1  S R  0.19  0.02  A
             2003 HM      21.7       0.19  0.04  A
        1036 Ganymed       9.5  S    0.18  0.06  A                      Ostro et al. 1991b
        7753 1988 XB      18.6  B    0.18  0.02  A
      101955 1999 RQ36    20.8  B    0.18  0.01  G
             2001 SG276   17.7       0.18  0.03  A
        7341 1991 VK      16.7  Q    0.17  0.02  A
      144901 2004 WG1     17.4       0.17  0.01  A
             2001 FR85    24.5       0.17  0.01  A
             2001 YP3     21.9       0.17  0.03  A
       13651 1997 BR      17.6  S    0.16  0.04  G
       65909 1998 FH12    19.1       0.16  0.03  G
      153591 2001 SN263   16.9  P    0.16  0.01  A
             2000 YA      23.7  S    0.16  0.02  A
             2001 SP263   25.6       0.16  0.02  A
             2002 TS69    24.5       0.16  0.02  A
             2004 VB      20.7       0.16  0.05  A
        1685 Toro         14.2  S    0.15  0.05  A                      Ostro et al. 1983 
      234145 2000 EW70    21.1  F    0.15  0.09  A
             2005 AB      17.5  C    0.15  0.04  A            BINARY
             2001 XX4     22.0       0.15  0.03  A
             2005 EK70    17.4       0.15  0.07  A
             2005 TD49    26.4       0.15  0.10  A
             2007 FY20    24.8       0.15  0.10  A
       29075 1950 DA      16.8  M    0.14  0.03  A G                    Busch et al. 2007
             1989 AZ      19.4       0.13  0.04  A
             2004 HX53    23.3       0.13  0.05  A
      141432 2002 CQ11    19.9       0.12  0.02  A
       99942 Apophis      19.7  Q    0.1   0.2   A                      Giorgini et al. 2008
             2002 AV      20.7  K    0.10  0.01  A
             2004 RF84    18.2       0.10  0.01  A
        6178 1986 DA      15.1  M    0.09  0.02  A                      Ostro et al. 1991a
             2001 UP      25.7       0.09  0.01  A
             2004 FY31    21.9       0.09  0.03  A
        4544 Xanthus      17.1  S    0.07  0.12  A                      Benner et al. 1997
             2005 XA      26.1       0.06  0.08  A
             2005 HB4     24.3       0.05  0.15  A
             2001 AV43    24.4       0.01  0.10  A
      163295 2002 HW      19.3       0.0   0.10  A
             2002 TZ66    25.9       0.0   0.2   A
             2006 QV89    25.2       0.0   0.25  A

N = 214  (counting 1999 KW4 Alpha and Beta as one object) 

Mean and rms dispersion = 0.336 +/- 0.248         
Median = 0.26                               

The taxonomy adopted is that described by Tholen and Barucci (1989) and Bus et al. (2002).  
The final version in the paper uses the Tholen system for simplicity; objects reported using the 
Bus taxonomy have been converted to Tholen's.  


Table 3: Spectral classes 

Last update: 2008 August 01

               NEAR-EARTH ASTEROIDS           MAIN-BELT ASTEROIDS
Taxonomic   <--------- SC/OC --------->    <--------- SC/OC -------->
Class       Mean   SD     Range  Number    Mean   SD    Range  Number
---------   ----   --     -----  ------    ----   --    -----  ------
  C         0.285  0.120  0.40     17      0.098  0.056  0.22   25        
  E         0.892  0.079  0.23      6      0.67   0.226  0.32    2  **  
  F         0.15   ----   ----      1      0.058  0.101  0.26    6
  G                                        0.102  0.080  0.20    5
  M         0.143  0.055  0.11      3      0.153  0.097  0.23    6  
  O         0.21   -----  ----      1     
  P         0.188  0.019  0.04      4      0.096  0.062  0.18    9    
  S         0.270  0.079  0.40     70      0.198  0.094  0.35   27    
  V         0.603  0.088  0.23      6      0.28   -----  ----    1  
  X         0.674  0.436  0.90      5    
  ?         0.339  0.284  1.48    101   

? = Taxonomy unknown
X = EMP (degenerate)
C = C- and B-types
S = S-, Q-, K-, L-, and R-types

Total = 214

** Hungaria and Nysa were observed by M. K. Shepard et al. 2007.  Radar observations of 
   E-class asteroids 44 Nysa and 434 Hungaria.  Icarus 195, 220-225.

   The other MBA results are from Magri et al. 2007, A radar survey of mainbelt asteroids:
   Arecibo observations of 55 objects during 1999-2003.  Icarus 186, 126-151.

POST-PUBLICATION UPDATES
2009 Sep 22   The table above does not include the reclassification of 65803 Didymos from
              the M class to the S class.
2009 Oct      The S classification for 2003 YT1 was added. This is not incorporated in the table above 
              due to the conflict with previous results obtained by Abell et al. 2005.
2009 Nov 02   Hicks and Barajas report that 1999 LF6 is an S-class object.  That has been
              updated in the SC/OC tables but is not reflected in the table of statistics above.
2010 Jan 21   Confirmation for 2006 VV2, 2007 DT103, and 1999 LF6 was reported by Binzel et al. 2010.
              The first spectral types for 4544 Xanthus, 6239 Minos, 2000 QW7, and 2001 BE10 were
              also reported by Binzel et al. 2010 and have been added to the master lists but
              are not included in the statistics above.
2010 Feb 18   Hicks et al. report that 4486 Mithra is an Sk or Sq-class object based on BVRI
              photometric colors obtained at Table Mountain Observatory.
2010 Jun 15   M. D. Hicks reports that 1999 MN is an Sq-class object.


Abundances by spectral class and comparison with meteorite falls Meteorite Abundance in the NEA sample Fall Statistics --------------------------- --------------- C 16/107 = 15.0% 40/930 = 4.3% (CI, CM, & other carbonaceous chondrites) E 6/107 = 5.6% 9/930 = 1.0% F 1/107 = 0.9% G 0/107 = 0.0% M 3/107 = 2.8% 40/930 = 4.3% (Irons; excludes stony-irons) O 1/107 = 0.9% P 3/107 = 2.8% S 66/107 = 61.7% 738/930 = 79.4% (H, L, LL ordinary chondrites; excluding E chondrites) V 6/107 = 5.6% 60/930 = 6.5% (HEDs--all three groups) X 5/107 = 4.7% ? 82/189 = 43.4%

Figure 1

Figure 2

Figure 3

Supplementary figures

Table COMET SC/OC
=================

Last updated: 2011 June 16

Comet                      Nucleus SC/OC   Year  Observatory
-----                      -------------   ----  -----------
2P/Encke                    No SC data     1980  Arecibo              Kamoun et al. 1982,    Harmon et al. 2004
                            0.21 +-0.04    2003  Arecibo              Harmon and Nolan 2005
26P/Grigg-Skjellerup       <0.3            1982  Arecibo              Kamoun et al. 1999,    Harmon et al. 2004 
73P/Schwassmann-Wachmann 3                                            Nolan et al. 2006 (reported the detection by not SC/OC)
  Fragment B                0.51 +-0.05    2006  Arecibo & Goldstone  X-band result shown   
  Fragment C                0.06 +-0.05    2006  Arecibo & Goldstone  X-band result shown
P/2005 JQ5 Catalina 3       0.49 +-0.05    2005  Arecibo              Harmon et al. 2006
C/IRAS-Araki-Alcock         0.105+-0.005   1983  Arecibo              Harmon et al. 1989,    Harmon et al. 2004
                            0.25           1983  Goldstone            Goldstein et al. 1984, Harmon et al. 2004
C/Sugano-Saigusa-Fujikawa   0.23 +-0.03    1983  Arecibo              Harmon et al. 1999     Harmon et al. 2004
C/Hyakutake                 0.49 +-0.10    1996  Goldstone            Harmon et al. 1997     Harmon et al. 2004
C/1998 K5 LINEAR           <0.5            1998  Arecibo              Harmon et al. 1999     Harmon et al. 2004
C/2004 Q2 Machholz          0.59 +-0.04    2004  Arecibo              Nolan et al. 2005
8P/Tuttle                   0.35           2008  Arecibo              Harmon et al. 2010
103P/Hartley 2              0.37           2010  Arecibo              Harmon et al. 2011

Comet nucleus detections = 11  (73P/S-W 3 is treated as two comets)

Mean SC/OC = 0.353 +- 0.195  
Range  = 0.485
N = 6 (ignoring estimates without uncertainties, those that are only upper limits, and 73P/SW3, which hasn't
       been reported yet).

Comets that did not yield nucleus detections: 
1P/Halley         1985   Arecibo
C/2001 A2 LINEAR  2001   Arecibo
C/2002 06 Swan    2002   Arecibo

Selected comet references:

Harmon, J. K., and M. C. Nolan.  Radar observations of comet 2P/Encke during the 2003 apparition.
  Icarus 176, 175-183 (2005).

Harmon, J. K., M. C. Nolan, S. J. Ostro, and D. B. Campbell.  Radar studies of comet nuclei and grain
  comae.  In Asteroids II, M. C. Festou, H. U. Keller, and H. A. Weaver, Eds., Tucson, Univ. of Arizona Press,
  pp. 265-279 (2004).

Harmon, J. K., M. C. Nolan, J. L. Margot, D. B. Campbell, L. A. M. Benner, and J. D. Giorgini.  Radar
  observations of comet P/2005 JQ5 (Catalina).  Icarus 184, 285-288 (2006). 

Harmon, J. K., M. C. Nolan., J. D. Giorgini, and E. S. Howell. Radar observations of 8P/Tuttle: 
  A contact-binary comet. Icarus 207, 499-502 (2010).

Harmon, J. K., M. C. Nolan, E. S. Howell, J. D. Giorgini, and P. A. Taylor.  Radar observations of 
  comet 103P/Hartley 2.  Astrophys. J. Lett., 734, L2 (2011).

Nolan, M. C., D. B. Campbell, J. K. Harmon, E. S. Howell, and C. Magri.  Arecibo radar detection of
  the nucleus and coma of C/2004 Q2 (Machholz).  In IAU Symposium 229, P14.21 [Abstract] (2005).