Gérard FAURE  -  DESCRIPTION OF THE SYSTEM OF ASTEROIDS AS OF MAY 20, 2004
		( Previous full description on 31-December-03 )
		English translation : Richard MILES
When I began observing asteroids in 1975, I knew hardly anything about them and data about them was not readily available to the amateur.
The research I undertook allowed me to discover their large number (several thousand at that time) and their orbital diversity within the Solar System.
It was thrilling to learn that these tiny and mysterious travellers wandered between and across the planets, crossing regions unknown to man.
I took an avid interest in them and in observing them as much as possible and learning the most about them.
Until the middle of the 1990s, each discovery, especially that of an Earth-Grazer was a notable event, and one could continue to have a good idea of the
composition of the minor planets on account of the limited number of new objects discovered annually.
When the era of automatic observation began and discoveries were made at an ever increasing rate, it was no longer possible to have a complete
knowledge of the structure and above all the composition of these tiny Liliputian worlds.
In September 2000, for the Meeting of the internet list of Alphonse Pouplier in the south-east of France, I had prepared an article presenting the asteroids, based
largely on numbered objects.
I had wanted to carry out a more complete analysis including unnumbered objects and the principal acquired knowledge on these asteroids.
This was done at the end of April 2002, in French and English.
Two updates followed : one partial one in French in August 2002, then a full and more comprehensive one at the end of 2003, translated into English by Richard Miles.
Lastly, for the presentation of this dossier at MACE 2004 ( Meeting on Asteroids and Comets in Europe ) in Frasso Sabino near Rome, I have proceeded to
update the data through to 20-May-2004.
Always with the help of the very useful spreadsheet Microsoft Excel, my personal and up-to-date library and the very useful MPCORB file from the Minor Planet
Center website, I have again spent a large part of my free time preparing, over a total period of 3 weeks, this "Description of the System of Asteroids"
in our Solar System to  20-May-2004.
214044 minor planets have been taken into account and I have processed, sorted, analysed and reanalysed nearly 3 million items of numerical data.
I have also newly drawn on information from dozens of recent professional articles and websites, for which references are given at the end of the analysis.
Due to a lack of time, the majority of statistics have not been updated since 2003.
For the first version in 2002, difficulties encountered had principally been :
Determining definite dynamical families and groupings within the Belt N°1 (notably the Nysa-Hertha, Griqua and Flora ones)
Assigning the TNOs to known or suspected families
The limiting zones of the variously-determined families and groups based on the orbital elements of the asteroids.
Updating the basic files as and when new MPECs (Minor Planet Electronic Circulars) are published.
For update at the end of 2003, which comprised numerous new categories, the difficulties were primarily :
Understanding and putting in summarised form current knowledge about the taxonomy and surface mineralogy of the minor planets.
Taking into account the advances in the knowledge of the structure of the Kuiper Belt.
Setting up files automating the various statistics presented in this file.
Updating all the precise orbital data for asteroids having often changed over 20 months at the level of tenths or hundreths of astronomical units,
sometimes even for definitively-numbered minor planets.
I have constructed the first analyses so as to give the largest possible number of readers, even those not fascinated by the asteroids, an accurate picture
of the various components making up the World of Minor Planets.
The initial pleasure has transformed itself into a very interesting work, requiring much research and allowing me to learn again and always, in spite of
the large number of years of reading already done.  It is also true that our knowledge about the asteroids is perpetually evolving…
As an Observer, I also take advantage of this work, which enables one to spot interesting objects to observe in the future.
Finally, certain analyses and statistics allow one to specify the limits and real extent of observational problems, bringing about a better appreciation
of planned work, sometimes contradicting previous ideas.
Of course, in spite of my attention, some errors or omissions have been made in the production of this work, which is published on the website of AUDE ( Association
des Utilisateurs de Détecteurs Electroniques, i.e. "Electronic Detectors Users' Association") , in that part reserved for the Magnitude Alert Project (MAP), jointly
managed by "The Minor  Planet Section  of the ALPO" (Association of Lunar and Planetary Observers) and by AUDE.
I would be grateful to you, if the case arises, if you would like to let me know by a message addressed to <gpmfaure@club-internet.fr> since it all adds something
useful. Thanks in advance.
I want to thank my friend Richard MILES (rmiles@baa.u-net.com), who at the MACE 2003 meeting in Mallorca offered his help for future English translations
of this dossier and its updates.
His very valuable contribution enables the near-simultaneous publication of the French and English versions, close to the very update of the scientific data included.
Lastly, I would like to draw your attention to the very interesting website of the Czech astronomer, Petr Scheirich, which can be found at the address :
" http://sajri.astronomy.cz/asteroidgroups/groups.htm "
A visit to his webpage "Asteroid Groups" enables, with the help of very fine images and graphics, to visualise many groups with various characteristics complementing
the account of the "System of Minor Planets" described below.
Good reading !
Gérard Faure
Asteroids taken into account
				Number on 31-Dec-03		Number on 20-May-04
The 85117 asteroids definitively numbered by the Minor Planet Center.				73636		85117
All other unnumbered asteroids from the MPCORB (MPC) file and/or the various lists on the MPC website				129966		128919
Certain probable NEAs dating from before 1990 and the possible Apohele 1998 DK36 (various sources)				8		7
The largest Plutino, Pluto				1		1
Particularly new discovered objects and notified in MPECs later than the download of the last used MPCORB file				2684		0
				206295		214044
NB: On 31-Dec-03, the MPC possessed 232740 asteroid orbits, of which 203605 were available in the MPCORB database and/or in the lists on the MPC website.
Those missing from MPCORB and the MPC lists are those of the most uncertain orbits. The objects concerned are effectively lost for the present.
Each day, new asteroids are discovered and orbits improved.
This update comprises 7749 minor planets additional to those at the end of 2003 and 58039 more than for the previous update to 28-April-2002.
NB: Satellites of asteroids are not counted in addition to the primary asteroid
Last remark before getting into the nitty-gritty of the subject: For practical reasons involving Excel (lack of space in certain tables, particular uses of brackets on
a French keyboard of a laptop PC, etc…), the official name format of definitively-numbered asteroids involving parentheses has not often been adhered to.
TERMS USED IN THE DESCRIPTION OF THE SYSTEM OF ASTEROIDS
a	Semi-major axis of the orbit or the mean distance from the Sun in AU
albedo	Percentage of sunlight that an object reflects from its surface.
e	Defines the degree of ellipticity of the orbit, from 0.0 (Circle) to >1.0 (Hyperbola)
family	A family is formed from asteroids having very similar values of "a", "e" and/or "i"
G	Defines the reflection of sunlight by the asteroid as a function of phase angle
group	A group is formed from asteroids situated in the same region of the Solar System having quite similar values of "a", "e" and/or "i"
H	The brightness in the V-band of an asteroid if at a distance of 1 AU from the Sun and 1 AU from the Earth
i	Inclination of the asteroid orbit from the Ecliptic in degrees
gap	Region of the Solar System devoid of asteroids owing to perturbations by a large planet (in particular resonance zones)
orbit	Path in space followed by a celestial body
P	Time required to complete one revolution of the orbit, in terrestrial years
Lagrangian Point	Stable orbital zone at 60° ahead of or behind the same orbit of a large planet ( zone "L5" westwards and zone "L4" to the east )
q	Perihelion or point in the orbit closest to the Sun, in AU
Q	Aphelion or point furthest from the Sun, in AU
resonance	The natural frequency of a physical system in the regions where the orbital period of the asteroids are at certain fractions of the
	period of a large planet.
AU	Astronomical Unit = approximately the Earth-Sun distance = 149 597 870 km.
NB: Other orbital elements exist. They are less descriptive but are indispensable for working out positional Ephemerides and the brightness of asteroids in the sky.
Examples : The "Longitude of the Ascending Node" of the orbit measured from the Vernal Equinox, the "Mean Anomaly" ( mean motion of the asteroid and the interval of time
since the asteroid passed perihelion), "the argument of perihelion" ( angle between the ascending node and the perihelion measured in the direction of the motion ), etc..
System of asteroid identification
Currently, new asteroid discoveries are subject to a 4-stage identification procedure, from the discovery to the definitive numbering :
In brief, the 4 stages are :
Stage 1 : Following discovery, the Discoverer assigns it a provisional designation ( Example : J002E3, P00ACE, SS-291, etc…)
Stage 2 : When the existence of the asteroid is confirmed, the MPC assigns it a provisional designation comprising the year of discovery, followed by
a letter, which defines the half-month in which the discovery was confirmed, and a second letter, usually accompanied by a number, defining
the sequential order of confirmation ; (examples : 1937 UB, 1980 AA, 2000 WR106, 2003 WT42, etc…).
Stage 3 : When the orbital elements become certain, the MPC assigns it a definitive number, which is indicated before the provisional designation.
Example: (20000) 2000 WR106
Stage 4 : Once definitely numbered, the Discoverer can name it.  Example: asteroid (20000) 2000 WR106 has become (20000) Varuna.
NB:  All asteroids have not followed these naming stages in the past and several provisional designations can be involved for the same object when it has been lost several times.
It is therefore, generally, the provisional designation that has yielded the definitive identification that is kept.
LARGE PLANETS:  Table of Minimum, Mean and Maximum Distances from the Sun
	q in AU	a in AU	a in millions of km	Q in AU		P in years
MERCURY	0.307	0.387	57.8	0.466		0.241
VENUS	0.718	0.723	108.1	0.728		0.615
EARTH	0.9833	1.000	149.5	1.0167		1.0
MARS	1.381	1.5236	227.9	1.6662		1.881
JUPITER	4.947	5.202	778.2	5.456		11.862
SATURN	9.030	9.578	1432.8	10.125		29.458
URANUS	18.171	19.129	2861.6	20.087		84.015
NEPTUNE	29.683	29.955	4481.2	30.227		164.788
(PLUTO)	29.620	39.496	5908.5	49.372		247.7
HISTORY of Minor Planets to 20-May-2004
16th Century		6 planets known, orbiting around the Sun:
		Planet                     Dist. in AU               Mean Dist. in millions of km
		MERCURY                      0.39                                       57.9
		VENUS                           0.72                                      108.1
		EARTH                           1.00                                      149.6
		MARS                            1.52                                       227.9
		JUPITER                         5.20                                      777.9
		SATURN                         9.54                                     1433.9
1596	Johannes KEPLER	The existence of a planetary body between Mars and Jupiter first mooted
		(Adaptation of Plato's Theory. Crystalline spheres of Ptolemy on 5 geometric solids
		each supporting a sphere.  One of these solids, the Tetrahedron, must support a sphere
		comprising a planet between the orbits of Mars and Jupiter.)
1766	Johannes TITIUS and	Titius-Bode Law : (n+4)/10 where "n" is an element from the series; 0, 3, 6, 12,...
	Johann BODE
		Planet                     Dist. in AU               Titius-Bode Prediction
		MERCURY                      0.39                        0.4
		VENUS                           0.72                        0.7
		EARTH                           1.00                        1.0
		MARS                            1.52                        1.6
		????                                                             2.8
		JUPITER                         5.20                        5.2
		SATURN                         9.54                      10.0
		There must therefore be a planet between Mars and Jupiter....
1781	William HERSCHEL	Discovery of the Planet URANUS located on average 19.2 AU from the Sun, that is 2.887 billion km.
		The Titius-Bode Law is again obeyed:  19.2 AU cf. 19.6 AU according to the law.
1785 to 1800	Baron Von ZACK (Hungary)	Search for the missing planet and start of the Zodiacal star catalogue in 1800.
31-Dec-1800	Guiseppe PIAZZI	Star in Taurus recorded on a chart at Palermo Observatory
01-Jan-1801	Guiseppe PIAZZI	Discovery of CERES followed until mid-February 1801.
		Thanks to calculations of Carl GAUSS, VON ZACH relocates Ceres on 07-Dec-1801
28-Mar-1802	Wilhem OLBERS	OLBERS fortuitously discovers PALLAS, having prepared star charts for observing Ceres.
01-Sep-1804	Karl HARDING	Olbers, thinking that Ceres and Pallas are two pieces from the same planet, asks for assistance.
		Karl HARDING finds JUNO on 01-Sep-1804.
29-Mar-1807	Wilhem OLBERS	Wilhem OLBERS finds VESTA on 29-Mar-1807.
1815		Search abandoned.  The Solar System is thus considered to comprise 11 planets.
		The word "asteroid" coined by William HERSCHEL in 1802 was used only after 1845.
08-Dec-1845	Karl HENCKE	Discovery of ASTRAEA after 15 years of solitary searching.
		Relaunch of the search for asteroids by the astronomical community, principally by amateurs.
23-Sep-1846	J.G. GALLE and	Discovery of NEPTUNE orbiting on average some 29.955 AU from the Sun, that is 4.481 billion km.
	U.V. LE VERRIER
End of 1849		10 asteroids are known. They are from now on called "asteroids" or "minor planets"
July 1868		100 asteroids are known.
		Daniel KIRKWOOD explains the gaps devoid of asteroids at certain average distances from the Sun as a
		result of the resonant action of Jupiter on the orbits of minor planets in the Asteroid Belt.
13-Jun-1873	James WATSON	Discovery of 132 AETHRA which at perihelion reaches the aphelion distance of Mars.
End of 1891		322 minor planets have been found, all visually.
		The record is held by Johann PALISA with 83 discoveries resulting from comparing the observed sky with
		that star charts extending sometimes to 15th magnitude !
20-Dec1891	Max WOLF	First photographic discovery of an asteroid : 323 BRUCIA
13-Aug-1898	Gustav WITT	Discovery of 433 EROS, first Earth-approaching asteroid, reaching 0.13 AU, that is 19.9 million km
Start of 1900		452 asteroids are known. Their orbits and their ephemerides are still derived by hand ...
		Data centres established at Berlin and Kiel.
24-Dec-1905		First Photographic Discovery by an amateur Joël H. METCALF ( 581 Tauntonia)  Taunton (USA) .
22-Feb-1906	Max WOLF	Discovery of 588 ACHILLES , first Trojan orbiting with Jupiter, at a Lagrangian point ( L4 )
20-Oct-1920	Walter BAADE	Discovery of 944 HIDALGO, which at aphelion reaches the vicinity of Saturn, at 9.54 AU.
1923		1000 asteroids recorded.
19-Feb-1930	Clyde TOMBAUGH	Discovery of PLUTO, the first trans-Neptunian object, orbiting at an average distance of 39.44 AU
		from the Sun (namely 5,900 billion km), but crossing the orbit of Neptune near perihelion.
24-Apr-1932	Karl REINMUTH	Discovery of 1862 APOLLO, first asteroid crossing the orbits of the Earth and Venus.
28-Oct-1937	Karl REINMUTH	1937 UB alias "HERMES" passes  733,000 km from the Earth.
1947		Minor Planet Center set up by the IAU under the direction of Paul HERGET.
		Start of the publication, "Ephemerides of Minor Planets" by the Institute of Astronomy, Leningrad
26-Jun-1949	Walter BAADE	Discovery of 1566 ICARUS, which approaches some 0.18 AU from the Sun, closer than Mercury.
05-Dec-1954	G.ABELL	Recovery of 1954 XA, the first ATEN asteroid orbiting on average closer to the Sun than the Earth.
10-Aug-1972		The Earth is skimmed at an altitude of 58 km by the "Montana Bolide" (USA) which returned to space.
11-Nov-1977	Charles KOWAL	Discovery of 2060 CHIRON, the first CENTAUR, having an orbit ranging from 8.43 to 18.84 AU ( that is
		2.8 billion km, not far from Uranus).
30-Jun-1978		The Minor Planet Center set up in Cambridge (USA) under the direction of Brian MARSDEN.
1989		Start of SPACEWATCH telescope operations on Kitt Peak, searching for asteroids making close approaches to Earth.
09-Jan-1992	Spacewatch - Kitt Peak	5145 PHOLUS, new Centaur discovered, situated at 32.2 AU, further than the average distance from the
		Sun of Neptune.
30-Aug-1992	D. JEWITT and J. X. LUU	Discovery of 1992 QB1, first TNO (Trans-Neptunian Object) not crossing the orbit of Neptune and
		orbiting at an average distance of 43.80 AU, namely 6.55 billion km from the Sun.
Sep-1992		First CCD discovery of an asteroid by an amateur: 1992 RA by N.KAWASATO
09-Dec-1994		1994 XM1 passes 112000 km from Earth, to date the closest Earth-crosser passage observed telescopically
09-Aug-1996	Palomar/NEAT and	Discovery of 1996 PW reaching 528 AU from the Sun, i.e. 79 billion km !
	Gareth WILLIAMS of the MPC
1997		Start of operation of the first LINEAR telescope (New Mexico) systematically combing the sky
Mar-1999		10000 numbered asteroids... Not including Pluto ( following discussions on the the status of this small
		planet or large asteroid )
29-Jul-2000	Cerro Tololo Observatory	Discovery of 2000 OO67 attaining a distance of 1016 AU from the Sun, that is almost 152 billion km !
		Its orbital period around the Sun is 11808 terrestrial years !
28-Nov-2000	McMILLAN and LARSEN	2000 WR106 is discovered by Spacewatch. This is the largest TNO discovered to date ( 900 km diameter )
Jan-2001		The 20,000th asteroid is numbered : 2000 WR106, which becomes (20000) Varuna
04-Jun-2002	TRUJILLO and BROWN	A very large TNO (1250 km diameter) 2002 LM60 is detected, visible to amateurs using CCDs.
	(Palomar/NEAT)
Nov-2002		50,000 numbered asteroids !!  2002 LM60 becomes known as (50000) Quaoar
11-Feb-2003	LINEAR	2003 CP20 is the first asteroid discovered orbiting entirely within the Earth's orbit.
21-Aug-2003	Deep Ecliptic Survey team	Confirmation of discovery of first Neptune-Trojan, 2001 QR322
15-Oct-2003	Brian SKIFF	After 66 years of searching, 1937 UB alias "Hermes" is found once more !
19-Feb-2004	(Palomar/NEAT)	2004 DW is a new TNO apparently larger than (50000) Quaoar, with an orbit of the Pluto type.
15-Mar-2004	BROWN et al	Announcement of the discovery of 2003 VB12 ( Sedna ), larger than 2004 DW and orbiting at 509 AU from the Sun !
	(Palomar/NEAT)
18-Mar-2004		The Aten 2004 FH pulverises the record for closest approach to the Earth, at 0.00033 AU, or 49367 km.
05-May-2004		The MPC has 251,002 asteroid orbit identified, of which 85,117 comprise definitively numbered objects.
		It is estimated that the number of asteroids exceeding 1 km in diameter reaches several million ....
		The hunt for new asteroids is thus far from over ....
SOURCES						Ref.G.Faure
Michel-Alain Combes		Deux siècles de découvertes d'astéroides - L' Astronomie Vol.115 janvier-février 2001				-
Tom Gehrels		History and Future - Asteroids -1979 T.Gehrels				<GF:FO>
Richard A. Kowalski		A Brief History of Minor Planet Research: The importance of the Amateur - Minor Planet				-
		Amateur/ProfessionalWorkshop 1999.
Minor Planet Center		Various data on asteroids ( http://cfa-www.harvard.edu/iau/mpc.html )				-
Syuichi Nakano		List of the first asteroids discovered by amateurs using CCDs
Frederick Pilcher and Jean Meeus		Tables of Minor Planets 1973				<GF:BK>
		TABLE OF THE SYSTEM OF MINOR PLANETS AS OF MAY 20, 2004
				Total	Total Identified		Number
GROUPS/FAMILIES	Orbital	Characteristics	Remarks	Numbered	as of 20-May-2004		Estimated
				1 to 85117	Number	Date	> 1 km
Within the Earth's orbit				0	3
VULCANOID	a < 0.22 AU	Q < q Mercury	Family still hypothetical	0	0	20-May-04	max. 900
APOHELE	a < 1.00 AU	Q < 1.00 AU	Orbit entirely within that of the Earth	0	2	20-May-04	20 ?
			1 (uncertain) = 1998 DK36		+ 1 ?
Near Earth Asteroids				339	2821	20-May-04	max.1200
ATEN	a < 1.00 AU	Q >1.00 AU	Aphelion external to q Earth	16	220	20-May-04
APOLLO				154	1354	20-May-04
APOLLO 1	q < 1.00 AU	a =1.00 to 1.524 AU	Crosses the Earth's orbit	74	594	20-May-04
APOLLO 2	q < 1.00 AU	a =1.524 to 2.12 AU	Crosses the Earth's orbit	48	433	20-May-04
APOLLO 3	q < 1.00 AU	a = 2.12 to 3.57 AU	Crosses the Earth's orbit	32	325	20-May-04
APOLLO 4	q < 1.00 AU	a > 3.57 AU	Crosses the Earth's orbit	0	2	20-May-04
AMOR				169	1241	20-May-04
AMOR 1	q < 1.30 AU	a =1.00 to 1.524 AU	Does not cross the Earth's orbit	22	225	20-May-04
AMOR 2	q < 1.30 AU	a =1.524 to 2.12 AU	Does not cross the Earth's orbit	66	422	20-May-04
AMOR 3	q < 1.30 AU	a = 2.12 to 3.57 AU	Does not cross the Earth's orbit	80	588	20-May-04
AMOR 4	q < 1.30 AU	a > 3.57 AU	Does not cross the Earth's orbit	1	6	20-May-04
NEA (uncertain)					6
Inside Belt N°1				1376	6790
MARS-CROSSER	q = 1.30 to 1.6662 AU	( a, i and e very varied )	Crosses Mars' orbit	638	3387	20-May-04
MARS-TROJAN EAST	a  ~ 1.524 AU	i > 16°	Lagrangian point L4 of Mars	0	1 ?	20-May-04	Total
MARS-TROJAN WEST	a  ~ 1.524 AU		Lagrangian point L5 of Mars	1	4 ?		50 ?
HUNGARIA	a = 1.76 to 2.06 AU	i = 12° to 36° /  e < 0.17	Between resonances 1:5 and 1:4	736	3375	20-May-04
Pre-Main-belt Objects	a = 1.88 to 2.06 AU	low i	Hungaria zone	1	23	20-May-04
BELT N°1	a = 2.10 to 4.02 AU			82417	201774	20-May-04	1 000 000
							to
			excl. Griquas, Cybeles, Hildas  =	81680	200179		1 400 000
							maximum
ZONE I  (INNER)	a = 2.065 to 2.501 AU		Between resonances 1:4 and 1:3	32221
Flora   (family?)	a = 2.12 to 2.27 AU	e = 0.04 to 0.21 / i < 8°	Between resonances 1:4 and 2:7		(3021)	2002
Phocaea (group)	a = 2.23 to 2.50 AU	e > 0.1 and i = 18 to 32°	Between resonances 2:7 and 1:3			(Morbidelli)
Vesta   (family)	a = 2.349 to 2.374 AU	e < 0.16 and i = 5 to 8°	Between resonances 2:7 and 1:4		(5575)	2002
Nysa-Hertha (family?)	a = 2.41 to 2.50 AU	e = 0.12 to 0.21 /  i < 4.3°	Between resonances 2:7 and 1:5		(6614)	2002
ZONE II (CENTRAL)	a = 2.501 to 2.820 AU		Between resonances 1:3 and 2:5	27179
Eunomia  (family)	a = 2.563 to 2.670 AU	e =0.07 to 0.21/ i =11 to 15°	Between resonances 1:3 and 2:5		(6162)	2002
ZONE III (OUTER)	a = 2.825 to 3.279 AU		Between resonances 2:5 and 1:2	22280
Koronis   (family)	a = 2.828 to 2.939 AU	e < 0.12 and  i < 3.5°	Between resonances 2:5 and 3:7		(2663)	2002
Eos         (family)	a = 2.988 to 3.046 AU	e < 0.13 and  i = 8 to 12°	Between resonances 3:7 and 4:9		(5188)	2002
Themis   (family)	a = 3.047 to 3.219 AU	e < 0.22 and  i < 3°	Between resonances 4:9 and 1:2		(2739)	2002
Hygiea   (family)	a = 3.108 to 3.217 AU	low "i" and moderate "e"	Between resonances 4:9 and 1:3		(1703)	2002
Griqua  ( Group ? )	a = 3.20 to 3.35 AU	e > 0.35 and i > 17°	In resonance 1:2 with Jupiter	5	20	20-May-04
CYBELE	a = 3.28 to 3.67 AU	e < 0.35 and i < 26°	Between resonances 1:2 and 3:5	357	702	20-May-04
HILDA	a = 3.74 to 4.02 AU	quite high e and i < 26°	In resonance 2:3 with Jupiter	375	873	20-May-04
Beyond Belt N°1				6	23
THULE	a = 4.28 AU	i = 2.3°	In resonance 3:4 with Jupiter	1	1	20-May-04
Internal Jupiter-crosser	a between 3.6 to 5.0 AU	high e ; isolated objects	Crossing towards Q the orbit of Jupiter	5	22	20-May-04
Jupiter-Trojans				877	1667		<2 million
JUPITER TROJAN EAST	a  = 4.90 to 5.37 AU	e < 0.30 and i < 40°	Lagrangian point L4 of Jupiter	525	1039	20-May-04
JUPITER TROJAN WEST	a  = 4.96 to 5.36 AU	e < 0.28 and i < 44°	Lagrangian point L5 of Jupiter	352	628	20-May-04
Beyond Jupiter				21	79
External Jupiter-crosser	a  > 5.1 AU	q < 5.1 AU and high e	Crossing towards q the orbit of Jupiter	5	25	20-May-04
CENTAUR	a = 5.5 to 29 AU	q > 5.2 AU / i < 35° / high e	"a" between Jupiter and Neptune	16	53	20-May-04
NEPTUNE-TROJAN EAST	a = 30.1 AU	e = 0.02  and i = 1.3°	Lagrangian point L4 of Neptune	0	1	20-May-04
NEPTUNE-TROJAN WEST	a ~ 30 AU		Lagrangian point L5 of Neptune	0	0	20-May-04
KUIPER BELT			( Discoverable if q < 52 AU )	81	887	20-May-04	millions ?
KBO Inner I	a = 30 to 35 AU	high e / q close to Uranus	q governed by Uranus ?	3	9	20-May-04
KBO 5:4	a = 35.0 AU	q < or = Q Neptune; i ~ 20°	Resonance 5:4 with Neptune	1	3	20-May-04
KBO Inner II	a= 36 to 38 AU	e<0.07-0.13 / q >Q Neptune	Inner Belt + Resonance 4:3 with N.	6	18	20-May-04
PLUTON+CHARON	a = 39.496 AU	q < Q Neptune	Resonance 3:2 with Neptune	0	1	20-May-04
PLUTINO	a ~ 39.5 AU	q near Q Neptune; i ~ 20°	Resonance 3:2 with Neptune	20	152	20-May-04
CUBEWANO	a = 40 to 47 AU	q >38 AU ; low "i" et "e"	( = Classical KBO )	27	450	20-May-04
KBO 5:3	a = 42.2 AU	high "e"	Resonance 5:3 with Neptune	2	7	20-May-04
( TNO uncertain )		TNO with"a"+"e" unknown			141	20-May-04
KBO 7:4	a = 43.9 AU	e > 0.2	Resonance 7:4 with Neptune	1	5	20-May-04
KBO 2:1	a ~48 AU	high "e" > 0.3	Resonance 2:1 with Neptune	2	10	20-May-04
Scattered Disk Object	a > 48 AU ?	q < 40 AU  and high "e"	( = SKBO )  ; q governed by Neptune	13	80	20-May-04
KBO 5:2	a ~ 55 AU	very high "e" > 0.4	Resonance 5:2 with Neptune	5	9	20-May-04
Extended Scattered Disk	a > 48 AU ?	q > 40 AU and high "e"	Existence still hypothetical	1	2	20-May-04
OORT CLOUD	a > 2000 AU ?	e > 0.9 and very large "Q"	a ~ 2000 to 10000 AU ?	0	0	20-May-04
							( 5 to 10
				85117	214044	20-May-04	million ? )
Remarks:
The assignment of each asteroid to a group is made following the official classifications :
*Majority from the position of their orbit relative to that of the Earth or of Mars, until and including the Mars-crossers, not taking into account their
semi-major axis.
*For distant objects, it is the position of their orbit relative to Jupiter and/or Neptune depending which dominates.
*I have classed Earth-crossers on the basis of the Earth's semi-major axis being equal to 1.000 AU, without taking into account the annual evolution of the Earth's orbit
between 0.983 and 1.017 AU.  In that, I have followed the rule employed by the Minor Planet Center.
I have not departed from the official nomenclature except for those types of object which are more or less unclassified at present :
*In the absence of a definitive nomenclature for those asteroids with orbits internal to that of the Earth, I have kept the designation "Apohele" which permits having a
fourth name for the 4th type of Earth-crosser orbit in addition to the Aten, Amor and Apollo.
Besides, Apohele allows one to adhere to the naming series based on the letter "A" for Earth-crossers.
Some minor planets of low inclination and eccentricity, located in the Hungaria zone, have nearly the orbital characteristics of the nearby Objects located in the inner edge
of the Belt N°1. I have called them "Pre-Main-belt Objects".
*Asteroids situated in the largely empty zones between the Hildas and Jupiter and crossing the Jovian orbit are called "Internal Jupiter-crossers".
*Unclassified asteroids beyond Jupiter, but crossing its orbit, have been named "External Jupiter-crossers".
*For the inner part of the Trans-Neptunian zone, I have split the present TNOs into "KBO Inner I" and "KBO Inner II", separated by the 5:4 resonance.
NB: The limiting zones of the families and groups within the Belt N°1 are based on the known limits for members clearly named in astronomical articles.
Evolution of the total numbers since the end of April 2002
Groups	end-April 2002	To 20 May 2004	Last update by the MPC	Increase in 25 months
Vulcanoids	0	0	20-May-2004	0
Apohele	1 ?	3?	20-May-2004	1
Atens	145	220	20-May-2004	75
Apollos	874	1354	20-May-2004	480
Amors	854	1251	20-May-2004	397
Mars-crossers	2396	3387	20-May-2004	991
Mars-Trojans	6	5 ?	20-May-2004	1
Hungarias	2227	3375	20-May-2004	1148
Belt N°1 ( excl. C and H )	146442	200179	20-May-2004	53737
Cybeles	509	702	20-May-2004	193
Hildas	568	873	20-May-2004	305
Jupiter-Trojans West	520	628	20-May-2004	108
Jupiter-Trojans East	787	1039	20-May-2004	252
Thule + Jupiter-Crossers	31	48	20-May-2004	17
Centaurs + Neptune-Troj.	34	54	20-May-2004	20
Internal KBO to CKBO	531	796	20-May-2004	265
SDO	74	89	20-May-2004	15
ESDO	1	2	20-May-2004	1
Oort	0	0	20-May-2004	0
Other Names of families and of groups of Minor Planets
Alinda	Asteroid undergoing libration in the 1:3 gap ( "a" ~ 2.5 AU, in the1:3 resonance with Jupiter )
CKBO	Second name for asteroids in the Kuiper belt, situated near 42 AU and with a low eccentricity, not crossing the orbit of Neptune.
Damocloid	Group derived from the Oort group of objects, with large "e", "i" and "a" reaching the interior part of the Solar System, often with "i" >90°
EGA	Asteroid which passes closer than 0.100 AU to the Earth's orbit
Earth-Grazer	Old name frequently used prior to that of "NEA".
Earth-crosser	An asteroid crossing the orbit of the Earth ( strictly Apollos or Atens ).
Griqua	Object on the outer edge of the Belt N°1, near 3.27 AU, with "i"  > 17° and e > 0.35 (resonance 1:2 with Jupiter)
IEO	Inner Earth Object = Object with orbit completely internal to that of the Earth. Another name for "Apohele"
KBO	Kuiper Belt Object
Kubewano	First name given to asteroids from the Kuiper Belt, located at about 42 AU and with a low eccentricity, not crossing the orbit of Neptune.
MBO	Belt N°1 Object
NEA	Near Earth Asteroid  = Asteroid approaching the Earth with q < 1.30 AU
NEO	Near Earth Object = Asteroid or comet approaching the Earth with q < 1.30 AU
Oort cloud object	Damocloid object
PHA	Potentially Hazardous Asteroid ( potentially dangerous ), with H < 22.0 and passing closer than 0.05 AU to the plane of the Ecliptic, at r = 1.0 AU
SDO	Scattered Disk Object = SKBO = Objects scattered from the Kuiper Belt, with "a" > 48 AU and "q" < 40 AU
SKBO	Scattered KBO = SDO = Objects scattered from the Kuiper Belt, with "a" > 48 AU and "q" < 40 AU
TNO	Trans-Neptunian Object = theoretically those situated beyond the orbit of Neptune
Vestoid	Small asteroid making up part of the dynamical family, Vesta, and exhibiting very similar spectral characteristics to those of 4 Vesta.
V-type	Asteroid exhibiting spectral characteristics similar to those of 4 Vesta, without being a member of the Vesta family.
Vulcanoid	Asteroide from a hypothetical belt, located within the orbit of Mercury, from 0.09 AU to 0.21 AU from the Sun.
	Recent studies indicate the possible existence of 300 to 900 Vulcanoids of more than 1 km diameter ( max. 25 km ),
	situated at a solar elongation of 4° to 12°, they will be difficult to detect, if they do indeed exist ….
Estimates of total asteroid numbers
All asteroids with:
Diameter > 1.0 km	> 3 million
Diameter > 0.1 km	billions
Earth-crossers:	( Spaceguard Data )
Diameter > 1.0 km	2 100
Diameter > 0.5 km	9 200
Diameter > 0.1 km	320 000
Diameter, 40 to 100 m	2 000 000
Diameter > 10 m	150 000 000
Following more recent estimates, the total number of Earth-crossers with diameter > 1 Km oscillates between 855+/-110 ( Morbidelli et al. en 2001) and 1200
( MPML 23-Jul-02 - Marsden data ). They are expected to comprise;  2% Atens, 23% Amors and 75% Apollos.
W.Bottke et al. indicate in their view a composition of; 6% Atens, 32% Amors and 62% Apollos, for NEAs with H < 22.
Those NEOs of mag < 18 would number 960 +/-120.
The NEA Search Report of NASA of Sep-2003 estimates at 1100 the number of NEAs > 1 km diameter, and at 500,000 those from 50 to 100 m in diameter.
Belt N°1:	( ISO Data )
Diameter > 1.0 km	1.1 to 1.9 million
The most recent estimates based on the Sloan Digital Sky Survey (SDSS) corrects for observing selection bias ( Asteroids III ) and indicates :
H < 12.0 = Actual	2858
H = 12	4600
H = 13	16000
H = 14	50000
H = 15	130000
H = 16	278000
H = 17	518000
Total > 1 km	1.0 to 1.4 million	( until H ~ 18.25 )
Kuiper Belt:
Diameter > 100 km	25,000 Plutinos	( David Jewitt data )
	45,000 Cubewanos	( David Jewitt data )
	>10,000 objects in the Extended Scattered Disk ( Data from B.Gladman et al. )
There should be, at the last estimates, around 100,000 TNOs greater than 100 km in diameter between 30 and 50 AU.
The recent estimates made at Kitt Peak National Observatory ( MPML 29-May-02 ) arrive at an inventory of 34 objects of the size of Charon and 4 the size of Pluto
which should be discoverable amongst the various TNOs.
Asteroids having changed family since definitive numbering (1985 to 2003) - Examples
1660 Wood	ex-Mars-Crosser	Belt N°1 ( Phocaea )	q Asteroid at the limit for Q of Mars
4015 Wilson-Harrington	ex-APOLLO 3	new AMOR 3	q Asteroid at the limit of "a" for the Earth; Comet.
4222 Nancita	ex-Belt N°1	new Mars-crosser	q Asteroid oscillates at the limit for Q of Mars
4587 Rees	ex-Mars-Crosser	new AMOR 3	q Asteroid oscillates at the boundary between the Amors and the Mars-crossers
5251 1985 KA	ex-Belt N°1 ( Phocaea )	new Mars-crosser	q Asteroid oscillates at the limit for Q of Mars
6263 1980 PX	ex-Belt N°1	new Mars-crosser	q Asteroid oscillates at the limit for Q of Mars
6454 1991 UG1	ex-Belt N°1	new Mars-crosser	q Asteroid oscillates at the limit for Q of Mars
6489 Golevka	ex-Amor 3	new APOLLO 3	q Asteroid at the limit of "a" for the Earth.
7747 Michalowski	ex-Mars-Crosser	Belt N°1	q Asteroid at the limit for Q of Mars
8722 Schirra	ex-Belt N°1	new Mars-crosser	q Asteroid oscillates at the limit for Q of Mars
18751 1999 GO9	ex-Belt N°1	new Mars-crosser	q Asteroid oscillates at the limit for Q of Mars
30555 2001 OM59	ex-Belt N°1 ( Phocaea )	new Mars-crosser	q Asteroid oscillates at the limit for Q of Mars
40310 1999 KU4	ex-Amor 3	new Mars-crosser	q Asteroid oscillates at the boundary between the Amors and the Mars-crossers
Comets numbered as asteroids
2060 Chiron	=	P/Chiron (95P)	Discovered as an asteroid in 1977, but considered to exhibit cometary activity in 1988
4015 Wilson-Harrington	=	P/Wilson-Harrington (107P)	Discovered as an asteroid but orbitally linked with a comet by B.Marsden in 1992
7968 Elst-Pizarro	=	P/Elst-Pizarro (133P)	"Comet" of dust with a stellar nucleus, orbiting in the Main Asteroid Belt.
NB: The asteroid-comet "Elst-Pizarro" is an exceptional object. This asteroid, from the dynamical "Themis" family, has shown cometary activity in 1996,
but was seen as stellar in 1979. The observation of a dust tail was repeated in 2002 thereby eliminating the possibility of a temporary dust tail in 1996, caused by a possible
collision. The two outbursts seem however to have been at a similar point in its orbit, perhaps indicating that a small part of the surface of the object, seasonally warmed
by the Sun, is responsible for the dust activity.
2201 Oljato, having an orbit similar to comet P/Encke has been suspected of gaseous emission similar to that of a comet in 1979 and in 1983.
Numerous other asteroids are suspected of being ancient comets, notably those possessing a comet-like orbit ( high eccentricity and inclination, …)
Examples:
5335 Damocles	Mars-crosser	a = 11.831 AU and e = 0.867	Halley-type orbit	H = 13.3
1996 PW	Oort  ?	a = 265.479 AU and e = 0.990	Oort Cloud origin ?	H = 14.0
Quite a large number of NEAs could be ancient extinct comets, sometimes linked with meteor streams.
According to estimates, the percentage of extinct comets amongst the NEOs ranges between 10 and 40%, with the greater likelihood being in the range, 25 to 40%.
There are about a dozen Earth-crossers which appear to be linked with meteor streams.
3200 Phaeton, an Apollo-type asteroid, is the nucleus of an extinct comet, associated with the Geminid meteors of the 14th December.
2101 Adonis and 1995 CS ( H ~ 25 ), having a similar orbit for the last 30,000 years, seem to be associated with 4 active meteor streams located in the
constellations of Capricornus and Sagittarius
(5496) 1973 NA has been associated with the Quadrantid meteor stream, but it is 2003 EH1 which appears to be the extinct parent body (IAU Circular 8252).
Meteor streams appear to contain small bodies several tens of meters in diameter.
In 2001, 17 objects from several meters to several tens of meters passed within several million km of the Earth having been found in the proximity of
the meteor radiants during the period of activity of the Capricornids,  Coma Berenicids, Leonids and Perseids.
APOHELE asteroids found or probable as of  20-May-2004
The first definite "Apohele" was discovered on 11-Feb-2003 :
Two Apoheles have been discovered to date :
2003 CP20	H = 16.5	a = 0.741 AU	q = 0.502 AU  and  Q = 0.9798 AU	e = 0.322	i = 25.61°	LINEAR
2004 JG6	H = 18.8	a = 0.633 AU	q = 0.294 AU  et   Q = 0.9723 AU	e = 0.633	i = 19.215°	LONEOS
These are the first asteroids known, for which the orbit is entirely contained within the Earth's.
Venus and Mercury are the only other known bodies in the Solar System orbiting closer to the Sun than the Earth.
2004 JG6 even has a semi-major axis smaller than that of Venus !
One other possible Apohele yet to be confirmed has been observed in 1998 :
1998 DK36	H = 25.0	a = 0.693 AU	q = 0.407 AU  and  Q = 0.980 AU	e = 0.413	i = 2.03°	(David THOLEN)
Around 20 Apoheles greater than one kilometer in diameter should exist, according to recent estimates.
The total number of Apoheles would be equivalent to only 2% of the total NEAs, according to Bottke et al..
An Earth-crosser can evolve dynamically to become an Apohele or IEA, names which have not yet been adopted by the MPC having classed 2003 CP20 and 2004 JG6 as Atens.
The terms Amor, Apollo and Aten specifically designate types of orbit close to the Earth: it would be regrettable not to set up a fourth orbital type.
NEAR EARTH ASTEROIDS  - Various Data
In the main, NEAs originate from five sources namely the resonances v6 and 1:3 ( Alindas ), the outer zones of the Belt N°1, Mars-crossers and the
family of comets perturbed by Jupiter and originating from the Kuiper Belt.
The main sources look to be the dynamical families from the Belt N°1 and the more distant TNOs or from the Oort Cloud.
Collisions between asteroids and moreover, the "Yarkovsky Effect" feed resonances capable of injecting new NEAs over several million years into
the inner Solar System.
Bottke et al. estimate that 61% of NEOs of H < 22 originate from the inner part of the Belt N°1, 24% from the central region, 8% from the outer zone
and 6% from the Jupiter family of comets.
TheYarkovsky Effect is a very weak thermal impulse when asteroid surfaces are heated by the Sun.  The effect particularly affects small asteroids, less than 10 km in diameter.
Certain Earth-crossers such as 1996 AJ1 ( Apollo 1 with a = 1.308 AU ) have 8 very close possible approaches (to less than 0.050 AU) to the Inner Planets of the Solar System.
Their lifetime is estimated to be very short.
The Amor  (6178) 1986 DA is in an orbit which permits a collision with Mars.
Some NEAs are in resonance with the Earth ; Examples :
887 Alinda	Resonance 3:1	'Leader' of a certain number of asteroids in 1:3 resonance with Jupiter, in the 1:3 gap
1221 Amor	Resonance 8:3	…and also in 2:9 resonance with Jupiter which with Earth govern the complex secular orbital variations
1627 Ivar	Resonance 11:28
3753 Cruithne	Resonance 1:1	Horseshoe orbit ("a" always between 0.997 and 1.003 AU with a cyclic variation in its orbital elements of 770 years)
NB: Other Earth-crossers could become "co-orbiters" to the Earth in the future, such as: 10563 Izhdubar, 3362 Khufu and 1994 TF2.
There could however be small asteroids (H > 20) in 1:1 resonance with the Earth. Very faint and dispersed across the sky, they would be very difficult to detect.
2002 AA29 ( a 100-m diameter asteroid ) travels along an orbit similar to that of the Earth, and has even been a satellite of the Earth in the past (around 550 AD
lasting 50 years).  It will do so anew in 2600 and 3880 AD !			a = 0.9975 AU / e = 0.012 / i = 10.74° / H = 24.3
Furthermore, certain asteroids such as 1991 VG and 2000 SG344 could be remnants from space vehicle launches, owing to the very strong resemblance of their orbital
elements to those of the Earth. The only definite case to date is J002E3 ( discovered by the amateur Bill Yeung ), which must be the third stage of the Saturn V rocket
from the launch of the Apollo 12 mission in 1970.  Other data are available at the web address: "http://www.projectpluto.com/probes.htm"
NEAs having common origins (a, e, i, related)
trio	433 Eros	1943 Anteros	1991 JR
pair	1566 Icarus	5786 Talos	( pieces from a broken-up parent comet ? )
pair	1620 Geographos	10115 1972 SK	( Asteroid pair, non-cometary origin )
pair	2101 Adonis	1995 CS	Linked with 4 active meteor streams => Joint cometary origin
pair	4015 Wolf-Harrington	1992 UY4	( pieces from a broken-up parent comet ? )
pair	6318 Cronkite	6322 1991 CQ
pair	1989 UP	1989 VB
pair	2201 Oljato	P/Encke	( fragments from an hypothetical Centaur named HEPHAISTOS ? )
NB: 2212 Hephaistos and 5143 Heracles could be fragments from an enormous Centaur which ventured into the Inner Solar System following a decrease
in its semi-major axis. It would have given birth to numerous NEAs or comets of which P/Encke is one, with "e" ~ 0.70-0.85 and low "i" (between 0 and 12°).
Nearly thirty NEAs belonging to this group could be found.
Examples of NEAs and numbered Mars-crossers of the type "Alinda" (i.e. "a" ~ 2.501 AU, in the 1:3 resonance zone with Jupiter)
887 Alinda	a = 2.485 AU	Amor 3	Type V = Fragment of Vesta ?	Resonance 4:1 with Earth
2608 Seneca	a = 2.503 AU	Amor 3
4179 Toutatis	a = 2.511 AU	Apollo 3
6318 Conkrite	a = 2.508 AU	Mars-crosser	q =1.341 AU
6322 1991 CQ	a = 2.515 AU	Mars-crosser	q =1.324 AU
6489 Golevka	a = 2.498 AU	Apollo 3	Type V = Fragment of Vesta ?
6491 1991 OA	a = 2.502 AU	Amor 3
7092 Cadmus	a = 2.523 AU	Apollo 3
13551 1992 FL1	a = 2.527 AU	Mars-crosser	q =1.459 AU
19356 1997 GH3	a = 2.492 AU	Amor 3
NEAs in resonance with Jupiter - Examples:
1221 Amor	Resonance 2:9	a = 1.919 AU	Amor 1	P = 2.659 years
6178 1986 DA	Resonance 2:5	a = 2.809 AU	Amor 3	P = 4.707 years
8567 1996 HW1	Resonance 1:4	a = 2.047 AU	Amor 2	P = 2.929 years
NEAs of Type 4 ( a > 3.57 AU beyond the Belt N°1 )
2003 WE42	Amor 4	a = 3.630 AU and e = 0.696	q = 1.101 AU and Q = 6.159 AU	H = 18.2	i = 34.9°
2001 XQ	Amor 4	a = 3.641 AU and e = 0.713	q = 1.043 AU and Q = 6.239 AU	H = 19.5	i = 28.99°
1982 YA	Amor 4	a = 3.707 AU and e = 0.697	q = 1.123 AU and Q = 6.291 AU	H = 16.5	i = 34.60°
1997 SE5	Amor 4	a = 3.730 AU and e = 0.666	q = 1.244 AU and Q = 6.215 AU	H = 14.8	i = 2.60°
2002 RN38	Amor 4	a = 3.799 AU and e = 0.674	q = 1.235 AU and Q = 6.362 AU	H = 17.3	i = 3.84°
5025 P-L	Apollo 4	a = 4.201 AU and e = 0.895	q = 0.439 AU and Q = 7.962 AU	H = 15.9	i = 6.20°
3552 Don Quixote	Amor 4	a = 4.232 AU and e = 0.712	q = 1.216 AU and Q = 7.248 AU	H = 13.0	i = 30.8°
1999 XS35	Apollo 4	a = 7.945 AU and e = 0.946	q = 0.421AU and Q = 15.468 AU	H = 17.2	i = 19.4°
The largest NEAs and their closest-approach distances to the Earth
NEA	Magnitude H	Diameter in km	Type of object	Closest Approach
1036 Ganymed	9.45	39	Amor 3	0.341 AU
433 Eros	11.16	33 x 13 x 13	Amor 1	0.124 AU
4954 Eric	12.6	12	Amor 2	0.194 AU
1866 Sisyphus	13.0	8	Apollo 2	0.102 AU
3552 Don Quixote	13.0	19 (very low albedo)	Amor 4	0.301 AU	( Extinct comet ? )
Frequency of passage by Earth-crossers close to the Earth
1 Earth-crosser 400 meters in size passes every 50 years at less than twice the Earth-Moon distance. ( MPML 03-Sep-02 )
1 or 2 Earth-crossers of 100 meters diameter pass by closer than the Moon each year ( Jim Scotti, MPML 24-Jun-02 )
NB: For the 'Earth-crossing' Comets, 180 of them of more than 1 km diameter cross the Earth's orbit each century (Spaceguard data ).
Some 2,400 or more 'lilliputians' of around 10 meters diameter pass closer than the Earth-Moon distance each year.
Very few of them are observed, as they reach magnitude 14 within 200,000 km of the Earth.  They shift very quickly across the sky and are bright for only a few hours.
For example, the large rock named 2003 XJ7 of H mag = 26.5 (~30 m) reached mag 13.4 on 06-Dec-03 at 0.0010 AU from the Earth, yet it only spent 8 hours when
it was brighter than magnitude 16.0, passing from an RA and Dec of 05h 41m and +45°, to 09h 36m and -67° !
From future predictions, it should be noted that 2000 WO107 ( H = 19.4 with diameter ~ 610 m ) could reach magnitude V + 5.0 in December 2140 !
Collisional frequency of NEAs with the Earth
These vary in the time and depend on the source of the estimates :
In 1979, Shoemaker estimated one collision of an object of 100 m diameter every 2,000 to 12,000 years or so.
20 to 40% of NEAs might be expected to collide with the Earth at some time in the future (Estimates: Wetherhill, 1979, and Shoemaker et al, 1990)
From 1975 to 1992, American spy satellites registered 136 explosions of mini-asteroids ranging from a few meters to 10 meters across in the atmosphere, even
though the instrumentation was only able to detect 10% of the explosions statistically-speaking.
A.Morbidelli et al. in 2001 estimated one collision with an Earth-crosser of H = 20.6 every 63,000 +/- 8,000 years. NEAs discovered to date only represent about 18%
of the potential impactors.  82% of them ( excl. Oort objects ) remain to be discovered …
Energy released	Impact interval	H equivalent	% of impactors yet to be discovered	Diameter
1000 megatonnes	63,000 +/- 8,000 yr	20.63	82	277 m
10,000 megatonnes	240,000 +/- 30,000 yr	18.97	63	597 m
100,000 megatonnes	925,000 +/- 121,000 yr	17.3	51	1287 m
1 impact of an NEA 50 meters in size occurs every century on Earth ( Jim Scotti, MPML 24-Jun-02 ).
2 impacts of an NEA some 100 meters in size occur every 1000 to 2000 years on Earth ( Jim Scotti, MPML 24-Jun-02 ).
In August 2003, some English and Russian researchers estimated that one body > 200 m in diameter would hit the surface every 160,000 years.
Their results relied on a study of the characteristic behaviour of the impactor during its travel through the atmosphere.
The NEA Search Report of NASA of September 2003 indicated an impact frequency of 1 object of 50-100 m every 1,000 years and of 1 object of 1 km
size every 500,000 years.
The same month, J.Scott of MIT announced in his view that one collision takes place with a 50-meter body every 2,000 to 3,000 years, and every 600,000
years for a body 1 km in diameter.
These results come from statistical analyses, which are in effect dependent on the magnitudes H and albedos of Earth-crossers, and also on the rate of formation
of craters in the lunar seas.
For dormant comets of the "Halley" type and those dormant for a long period, the collisional probability ( 2002 ) is respectively once every 370 and 780 million years.
On the 16th March 2880, (29075) 1950 DA has a 1 "chance" in 300 of entering into a collision with the Earth, according to the known stable orbital elements.
It should also be pointed out that currently, there are about 50,000 meteorites which fall to earth each year (MPML 24-Sep-02).
The oldest NEAs lost from 20 years ago or more
5025 P-L	Apollo 4	H = 16.9	a = 2.255 AU and q = 0.625 AU	Palomar Leiden Survey in September 1960
6344 P-L	Apollo 3	H = 21.5	a = 2.379 AU and q = 0.949 AU	Palomar Leiden Survey in September 1961
1972 RB	Amor 3	H = 19.7	a = 2.149 AU and q = 1.105 AU	Gehrels - 49-day arc
1977 VA	Amor 2	H = 19.0	a = 1.864 AU and q = 1.130 AU	E.Helin - 93-day arc
1979 QA	Apollo ?	?	a =  ? AU and q < 1.0 AU ?	Palomar
1979 QB	Amor 3	H = 17.4	a = 2.329 AU and q = 1.296 AU	E.Helin - 67-day arc
1979 XB	Apollo 3	H = 19.0	a = 2.262 AU and q = 0.649 AU	K. S. Russell
1980 QA	NEA ?	H = ?	?	?
1981 JD	NEA ?	H = ?	?	?
1982 CA	NEA ?	H = ?	?	?
1982 EA	NEA ?	H = ?	?	?
1982 YA	Amor 3	H = 16.5	a = 3.707 AU and q = 1.123 AU	F. Dossin
1983 LB	Amor 3	H = 16.5	a = 2.287 AU and q = 1.194 AU	E. F. Helin, R. S. Dunbar - 56-day arc
1983 LC	Apollo 3	H = 19.0	a = 2.632 AU and q = 0.766 AU	E. F. Helin, R. S. Dunbar
1983 SN	NEA ?	H = ?	?	?
1983 VA	Apollo 3	H = 16.5	a = 2.609 AU and q = 0.800 AU	IRAS Satellite - 189-day arc
The oldest lost NEAs recovered since 2000
719 Albert	Amor 3	H = 16.0	a = 2.584 AU and q = 1.188 AU	Found on 03-Oct-1911
	= 2000 JW8	H = 15.8	a = 2.637 AU and q = 1.184 AU	recovered on 01-May-2000
1937 UB   Hermes	Apollo 2	H = 18.0	a = 1.639 AU and q = 0.616 AU	observed in 1937 (4-day arc)
(69230)		H = 17.5	a = 1.654 AU and q = 0.621 AU	recovered on 15-Oct-2003
1950 DA	Apollo 2	H = 15.9	a = 1.683 AU and q = 0.838 AU	observed in 1950 (17-day arc)
(29075)	= 2000 YK66	H = 17.0	a = 1.699 AU and q = 0.837 AU	recovered on 31-Dec-2000
1954 XA	Aten	H = 18.5	a = 0.687 AU and q = 0.261 AU	1st Aten, observed in 1954 (6-day arc)
	= 2003 UC20	H = 19.2	a = 0.781 AU and q = 0.517 AU	recovered on 21-Oct-2003
4788 P-L	Amor 3	H = 16.9	a = 2.612 AU and q = 1.153 AU	Palomar Leiden Survey of September 1960
	= 2003 SV84	H = 16.7	a = 2.629 AU and q = 1.155 AU	recovered on 20-Sep-2003
1978 CA	Apollo 1	H = 18.0	a = 1.125 AU and q = 0.883 AU	observed for 32 jours in 1978
		H = 17.1	a = 1.123 AU and q = 0.883 AU	recovered on 11-Jan-2003
1975 XA	Apollo 3	H = ?	a =  ? AU   et q < 1.0 AU ?	Wroblewsky - Mag.11 seen - December 1975
	= 2004 JN13	H = 14.6	a = 2,868 AU et q = 0,867 AU	recovered on 23-Apr-2004
MARS-CROSSERS with large "a" and "e"
Mars-crossers are probably produced by various resonances caused by Jupiter ( resonances v6 or 3:1 for example ), Mars and also by the combined
pair of Jupiter-Saturn.
These resonances slowly increase the eccentricities of the asteroids in the Belt N°1 until their perihelia reach the orbit of Mars,
The Mars-crosser population also evolves as a function of the variations in the eccentricity of Mars itself ( 0.01 to 0.12 ) over 2 million years.
Thus objects having a q ~ 1.6 AU to 1.78 AU are able to cyclically become Mars-crossers.
Certain asteroids such as 5335 Damocles (q = 1.572 AU, a =11.831 AU, Q=22.091 AU) could be called a Mars-crosser (based on q), Jupiter-crosser,
Centaur (based on "a"), Saturn-crosser and Uranus-crosser (based on Q). Certain of these are no doubt ancient comets.
1997 MD10 is even a Neptune-crosser !
The 3 examples of Mars-crosser having large "a" are:
5335 Damocles	q = 1.572 AU	a = 11.831 AU	Q = 22.091 AU
1998 WU24	q = 1.425 AU	a = 15.216 AU	Q = 29.006 AU
1997 MD10	q = 1.545 AU	a = 26.581 AU	Q = 51.618 AU
Possible MARS-TROJANS as of 20-May-04
5261 Eureka	Lagrangian point L5	H = 16.1	r = 1.425 to 1.622 AU	First Mars-Trojan discovered in 1990
1998 VF31	Lagrangian point L5	H = 17.4	r = 1.371 to 1.677 AU
1999 UJ7	Lagrangian point L4	H = 17.0	r = 1.465 to 1.584 AU	Doubtful, being at 11H in R.A.of Mars at end-2003
2001 DH47	Lagrangian point L5	H = 19.7	r = 1.468 to 1.572 AU
2001 FG24	Lagrangian point L5	H = 21.3	r = 1.319 to 1.717 AU
2001 FR127	Lagrangian point L5	H = 19.0	r = 1.354 to 1.692 AU
2003 SC220	Lagrangian point L4	H = 20.1	r = 1.331 to 1.710 AU	Doubtful, being at 1.5H in R.A.of Mars at end-2003
NB: The existing list in October 2003 ( prior to the recent case, 2003 SC220 ) has been put in doubt by the MPC who will only reintroduce Mars-Trojans when these objects
are confirmed by long-term integrations using good orbits.
Nearly 50 or so Mars-Trojans larger than a kilometer could exist.
Trojan orbits near to Mars are very stable.
Photometric and spectroscopic studies of 3 of the Mars-Trojanshave not revealed any striking similarities between them ( 5261 Eureka, 1998 VF31 and 1997 UJ7 )
There must therefore not have been a common origin for these objects.
5261 Eureka and 1998 VF31 are however of a rare mineralogical type ( Sr/A ) not common in Belt N°1.
2003 OX7 ( a = 1.5293 AU ) is virtually on the same orbit as Mars, but is not a Mars-Trojan.
It made its closest approach to Mars on 4 July 2003 at 0.045 AU, at least for the period 1800-2200  (MPML 02/09/03).
MAIN BELT  ( or BELT N°1 ) : Data and various remarks
One personal remark to begin with : The discovery of many large asteroids of mag H < 4.5 in the Kuiper Belt, and the fact that the First (trans-Martian) Belt only
contains 3 may be considered to render the name "Belt N°1" obsolete for this first region of asteroids.
The dimensions and divisions of the Belt N°1 are principally due to gravitational perturbations created by Jupiter.
The total mass of this trans-Martian belt is estimated to be about 18 X 10^-10 of the solar mass.
The zones in resonance with Jupiter are either empty of asteroids (Kirkwood gaps) or stable zones populated by groups of asteroids.
More than 99% of primordial asteroids would have been ejected in one million years from the Solar System through perturbations from the larger embryonic planets.
TheYarkovsky Effect ( thermally-induced impulse from solar heating of the asteroid surface ) shifts the small objects ( e.g., by 0.04 AU in 100 million years
for those of 1 km diameter in the Flora zone ) and contributes to emptying the Solar System of those small asteroids, which enter a resonance zone,
finishing by either hitting the Sun or a planet, or by being ejected from the Solar System.
With the Yarkovsky Effect, passage close to one of the large asteroids in the Belt can also cause a variation in the orbit of small bodies (0.00075 AU in the case of (1) Ceres).
At the end of 1997, those asteroids of mag H < 12.75 , 12.25 and 11.25 (inner, middle and outer regions of the Belt N°1) were considered to have been all found.
In 2002, nearly all asteroids from the Belt N°1 up to H = 13.0 had been discovered.
At least one third of asteroids from the Belt N°1 are part of asteroid families arising from the fragmentation of larger asteroids following collisions.
It is with the aid of the "proper" orbital elements ( a' , e' and sin i ' ) valid over a million years that dynamical families are determined.
As time passes, the families become diluted and are less recognisable, following possible collision,  and evolution of the proper elements of the asteroids.
There may be about 64 groupings of asteroids, of which 32 dynamical families are certain.
9 Metis and 113 Amalthea, which exhibit near-identical spectrophotometric data, probably arose from the same parent body of 300 to 600 km size.
The most recent family identified is the "Karin" family ( 13 objects with the parent, 832 Karin of 20 km diameter ) which came about as a result of the fragmentation
of an asteroid of 27 km in size, 5.8 million years ago.
The "Flora" family :
It is composed of different sub-families owing to successive collisions arising most probably 500 million years ago ( 900 million years ago at most).
Various non-members have already been identified by their different taxonomic type to type S of Flora : 298 Baptistina, 2093 Genichesk, 4278 Harvey, etc..
The parent body of the "Floras" would have had a mass 1.75 times larger than (8) Flora itself with a diameter of 164 km.
8 Flora could be the major constituent part from the central region of a large fragmented asteroid.
8 Flora (136 km in diameter) and 43 Ariadne (66 km) appear to be the two biggest members of the Floras, the others being hardly 30 km across or less.
951 Gaspra, visited by the space probe Galileo, is most likely a fragment from the Flora parent body (same type S and similar orbital elements).
With a semi-major axis of 2.256 AU from the Sun and resonances with Jupiter (2:7) and Mars (9:4), there would have been a significant loss of small "Floras" to the
Mars-crossers.
The "Flora" family would have lost 3% of its members over a 100 million-year period, to the benefit of the Mars-crossers.
The Flora and the Phocaea families situated at the inner edge of the Belt N°1 and the v6 resonance would be the main source of the Mars-crossers which after become NEAs.
The Phocaea group
Located in a region having the 3:1 resonance, their orbits have a large inclination and eccentricity.
This group, having particular proper elements, is quite isolated in an 'islet' of stability with limits defined by the action of the main or secular resonances.
They never make close approaches to Mars.
It is not possible to know whether Phocaeas comprise members of a group having similar orbital elements or members of a family originating from the break-up of a
large asteroid.
The "Vesta" family :
It is composed of 4 Vesta and various small asteroids in similar orbits and of a near-identical reflectance spectral type V, related to Pyroxene and close to that of
basaltic HED ( Howardite, Eucrite and Diogenite) meteorites. These small objects are called "Vestoids" and may be pieces of the crust of Vesta, torn away
by collision.  Together, the Vestoids are believed to be equivalent in volume to a crater 100 km across and 7 km in depth.
In 1997, the Hubble Space Telescope (HST) found on the globe of Vesta, a formation which could be the sign of a very large crater.
Furthermore, 2579 Spartacus may have a spectral signature similar to the mineral, Olivine, and which could be regarded as a mixed piece of "mantle and
crust" of 4 Vesta.
1929 Kollaa ( the largest Vestoid with d = 15 km ) could arise similarly from the deep layer of Eucrite from 4 Vesta
However, other asteroids also exhibit type V even though they are distant from Vesta.  They might be the survivors from another fragmented basaltic asteroid.
The Yarkovsky Effect, which can alter the semi-major axis by 0.0001 AU each million years, could be the main cause for the diffusion of the Vesta family.
The ejection velocity of the fragments from Vesta or their subsequent acceleration through dynamic evolution could also have directed them close to resonances injecting
them into other zones of the Solar System, such as the region of the NEAs.
Several examples of non-Vestoid asteroids of type V :
809 Lundia ( the biggest non-Vestoid V-type known : d = 9.1 Km ) and 4278 Harvey ( d = 3.3 km ), situated in the Flora zone
1459 Magnya of 30 km diameter, situated at a = 3.14 AU in the outer region of the Belt N°1, quite far from 4 Vesta and the only large object of type V in that area.
The "Eunomia" family :
15 Eunomia represents 70% of the initial mass of the parent body estimated at 284 km in diameter.
We know of 110 members larger than 11 km making up the Eunomia family.
The "Adeona" family :
The age of this family appears to be around 600 million years.  It is large having 648 members as of 2002.
The "Gefion" family :
The age of this family appears to be around 850 million years.  Located in the central part of the the Belt N°1 ( a =  ~ 2.78 AU ), it comprises 37 known members
as of 1995, and 973 members as of 2002, but remains a minor family within the Belt N°1.  The asteroid 1 Ceres orbiting in this zone does not make up part of the Gefion family.
The "Eos" family :
The "Eos" family seems to have arisen from successive collisions between asteroids dating from more than a billion years ago.
Several rings of dust have been found by the space probe, IRAS, notably in proximity to the Eos and Themis families.
The small members (H>13) of this family will feed the closeby 7:3 resonance, as a result of the Yarkovsky Effect.
The "Koronis" family :
The "Koronis" family seems to have arisen from successive collisions between asteroids.
The age of this family is estimated at 1.5 billion years, based on crater counts on 243 Ida imaged by the space probe Galileo in 1993.
The Koronis parent body looks to have been decimated, in that 158 Koronis is estimated to make up only 4% of the initial mass of the parent body of diameter, 119 km.
As with the Eos family Eos, the small members ( H>13) of this family will feed the closeby 7:3 resonance, as a result of the Yarkovsky Effect.
2953 Vysheslavia, a member of the Koronis family, very close to the outer edge of the 2:5 resonance, could be ejected from the Solar System during the next 10 million years.
A recent study of the rotational axes of nearly a dozen members of the Koronis family, 25 to 45 km in size, has shown that the axial alignments fall into two groups of 4 and 6
asteroids, according to whether rotation is prograde or retrograde.
In spite of the random primordial distribution of rotational axes following on the initial collision, orbital resonances with Saturn and the Yarkovsky Effect together will have forced
an axial realignment for these Koronis objects (the so-called "Slivan state").
Thermal pressure arising diurnally at the asteroid surface could also ( depending on the nature of the shape, surface and rottation of the asteroid) have realigned the
axes of the Koronis objects. This long-term effect is named YORP after the name of its discoverers ( Yarkovsky, O'Keefe, Radzievsky and Paddick )
These objects also appear to possess, on average, a larger lightcurve amplitude than other objects from the Belt N°1.
The "Themis" family :
The family named "Themis" appears to be the result of the break-up of one of the large asteroids ( originally one 380 km in diameter ), some 2 billion years ago.
Given that the cometary asteroid 7968 Elst-Pizarro belongs to the "Themis" dynamical family, it could be that the parent body of the "Themis" family had been of mixed
nature (part-asteroid, part-comet) such as a large body displaced from the Kuiper Belt. Soon after fragmentation, the numerous pieces must have generated cometary activity.
The Griqua group :
The asteroids of the Griqua type, located at the limit of the outer sub-belt, near 3.28 AU ( to be found between 3.10 and 3.27 AU ) is only distinguished from the rest of
nearby asteroids through their high eccentricities exceeding the (arbitrary ?) limit of 0.35.
The Griquas are close to the 1:2 resonance with Jupiter and are protected from planetary interaction by librations about this resonance.
Their remaining in this resonance will only last between 1,000 and 1 million years.
Some amongst them could be ancient Centaurs.
Personal remark : On analysing orbital elements of asteroids situated in the region, a = 3.0 to 3.5 AU, asteroids are found having eccentricities and inclinations,
which are weakly spaced out, up until the Griquas and even beyond. Potential Griquas having very high eccentricity find themselves becoming Mars-Crossers.
If from the elements of the Griquas themselves it is not possible to differentiate them from other objects in this zone, then they probably do not form a separate group….
Principal resonances with Jupiter  ( x:y  means: "x" revolutions of Jupiter for "y" revolutions of the asteroid in the same time)
Solar Distance	Resonances	Kirkwood Gaps	Groups found:	P in years
a = 1.778 AU	1:5			2.372
a = 1.908 AU	2:9		Hungaria
a = 2.065 AU	1:4	Resonance v6		2.965
a = 2.256 AU	2:7	(NB: Also corresponds to a 9:4 resonance with Mars)
a = 2.501 AU	1:3	Hestia Gap	Alinda	3.954
a = 2.706 AU	3:8
a = 2.825 AU	2:5	Gap
a = 2.956 AU	3:7	Gap	(Between Koronis and Eos families)
a = 3.030 AU	4:9	-
a = 3.278 AU	1:2	Hekuba Gap	Griqua	5.931
a = 3.700 AU	3:5	Gap	(between Cybeles and Hildas)
a = 3.969 AU	2:3	-	Hilda	7.908
a = 4.03 to 4.29 AU		Empty zone	(between Hildas and Thule)
a =  4.293 AU	3:4	-	Thule	8.896
a = 4.29 to 4.90 AU		Empty zone	(between Thule and Trojans)
a =  5.203 AU	1:1	-	Jupiter-Trojans	11.862
NB: Other less marked resonances exist such as those of 5:9, 7:4, 5:8, 7:12, etc…
All these resonances are so-called "mean motion resonances", which can be misleading in that orbital
variations can take place over a short time-scale, of the order of 1000 years.
There also exist so-called "secular resonances", connected with the precession of the orbits of bodies interacting.  A small body in secular resonance with a large
planet sees it's orbit precess in the same manner as a planet's orbit.
These secular resonances act over very long periods of over a million years, and produce changes to various orbital elements such as eccentricity and inclination.
The v6 secular resonance ( pronounced "nu 6") is a resonance which acts when the rate of precession of longitudes of perihelia of asteroids correspond with those of Saturn.
This resonance delineates the inner edge of the Belt N°1.
This v6 resonance and that of 3:1 should be the most prolific in generating new NEAs ( 100-160 objects and 40-60 objects with H<18 respectively ).
The orbital elements of perturbing planets evolve with time, such that resonances shift in interplanetary space.
Resonances are not necessarily empty. The 7:3 resonance actually contains at least 23 asteroids temporarily trapped through the action of the Yarkovsky Effect.
They are all small asteroids with the exception of 677 Aaltje (diam. 30 km), perhaps having been pushed into the resonance through the proximity of 1 Ceres.
Personal remark:
In the various articles on resonances explored, one comes across two types of representation for the same resonances, involving Jupiter.
For example: the 3:2 or 2:3 resonance, the 9:2 or 2:9…..
To ensure conformance between resonances involving Jupiter and those of the TNO zone, I have therefore standardised on the description of resonances
by using the following format : " x revolutions of the major Planet : y revolutions of the Asteroid"
Therefore, the "3:5" resonance defines the gap separating the Cybeles and Hildas (3 orbital revolutions of Jupiter for 5 of an object at 3.7 AU) and the resonance "5:3"
defines that located in the CKBO zone near 42 AU (5 revolutions of Neptune for 3 of a KBO, hence 5:3)
Number of members of the main dynamical families in the Belt N°1, in 1995 and in 2002
Families	HCM Method 1995	WAM Method 1995	Estimated number of objects diam. > 5 km		Morbidelli et al 2002
Flora	604	575	709		3021
Nysa / Hertha	381	374	?		6614
Vesta	231	242	402		5575
Ceres/Minerva	89	88	?		-	Family not sure
Maria	77	83	654		1776
Adeona	63	67	1430		648
Dora	77	79	310		419
Eunomia	439	303	2748		6162
Hygiea	103	175	> 10000		2663
Koronis	325	299	729		2663
Eos	477	482	4131		5188
Themis	550	517	9825		2739
HCM Method	= Hierarchical Clustering Method  (Zappala et al.)				See references
WAM Method	= Wavelet Analysis Method (Bendjoya et al.)				See references
Morbidelli et al 2002	= HCM method used with 106284 minor planets having proper elements ( Knezevic and Milani )				See references
NB: The Nysa zone is populated by various families depending on the author: Nysa, Hertha, Polana, etc…
The Hertha and Nysa families are apparently distinguished by a narrow void and a distinct difference in orbital inclination.
The "Maria" family is situated on the edge of the strong 3:1 resonance and may furnish the NEA zone with large Earth-crossers.
Numbers and H magnitudes of the 4 main members of the principal dynamical families from the asteroid belt :
The number and composition of the members of each family differ according to the authors of the studies, the assignment of an asteroid to one or other family is not
still 100% certain. From a study by P. Bendjoya, the largest 4 asteroids for sure for each of the principal dynamical families are :
Family
Flora	8 Flora  ( H = 6.49 )	43 Ariadne  ( H = 7.93 )	367 Amicitia  ( H = 10.7 )	770 Bali  ( H = 10.93 )
Nysa + Hertha	44 Nysa  ( H = 7.03 )	135 Hertha  ( H = 8.23 )	1493 Sigrid   ( H = 11.99 )	1650 Heckmann  ( H = 11.56 )
Vesta	4 Vesta  ( H = 3.20 )	63 Ausonia  ( H = 7.55 )	2346 Lilio  ( H = 11.9 )	2086 Newell  ( H = 12.4 )
Maria	170 Maria  ( H = 9.39 )	472 Roma ( H = 8.92 )	660 Crescentia ( H = 9.14 )	714 Ulula ( H = 9.07 )
Eunomia	15 Eunomia ( H = 5.28 )	1275 Cimbria ( H = 10.72 )	1329 Eliane ( H = 10.90 )	1503 Kuopio ( H = 10.6 )
Koronis	158 Koronis ( H = 9.27 )	167 Urda ( H = 9.24 )	208 Lacrimosa ( H = 8.96 )	462 Eriphyla ( H = 9.23 )
Eos	221 Eos ( H = 7.67 )	579 Sidonia ( H = 7.85 )	639 Latona ( H = 8.20 )	653 Berenike ( H = 9.18 )
Themis	24 Themis ( H = 7.08 )	62 Erato ( H = 8.76 )	90 Antiope ( H = 8.27 )	171 Ophelia ( H = 8.31 )
Families of 50 to 100 members and groups known ( in 1995 ) :
Phocaea	a = 2.23 to 2.50 AU	e > 0.1 and i = 18 to 32°	grouping of objects from the Inner Belt having high orbital inclination
Polana	a ~ 2.4 AU	Family of the 'clan', Nysa	Dynamical family, by the WAM method (102 members known in 1994)
Alinda	a ~ 2.50 AU	1:3 resonance with Jupiter	Earth-crossers in libration with Jupiter
Pallas	a = 2.50 to 2.82 AU	i = 33 to 38°	Dynamical family	(More than 10 members found as of 1994)
Maria	a =2.526 to 2.591 AU	e< 0.11 and i < 27°	Dynamical family	(74 members found as of 1994)
Adeona	a =2.661 to 2.688 AU	e< 0.18 and i < 21°	Dynamical family	(61 members known for certain by 1994)
Dora	a =2.763 to 2.813 AU	e< 0.20 and i < 14°	Dynamical family	(75 members known for certain by 1994)
NB: The Phocaea group distinguish themselves from other asteroids of the inner Belt N°1 by high inclinations and extend as far as the Mars-crossers, which differ from
Phocaeas only by their larger eccentricity to cross the orbit of Mars.
The Hilda group
Situated in the 2:3 resonance with Jupiter, these asteroids reach aphelion passing in front of the Lagrangian points of Jupiter or in being in opposition with Jupiter,
thereby avoiding capture by Jupiter.  They pass perihelion facing Jupiter or at 120° of longitude to the giant planet.
Thus the Hilda group define a triangle in rotation with Jupiter around the Sun.
The Hildas, which have less stable orbits than the Jupiter-Trojans, are expected to be the principal source of cratering of the Galilean satellites.
Numbered "internal Jupiter-crossers" with a < a of Jupiter and q > Q of Mars from the 85117 numbered asteroids
5164 Mullo	a = 3.645 AU	Q = 5.486 AU
6144 1994 EQ3	a = 4.785 AU	Q = 6.520 AU
20898 Fountainhills	a = 4.226 AU	Q = 6.192 AU	"a" similar to 279 Thule, but "e" and "i" larger
32511 2001 NX17	a = 5.053 AU	Q = 7.212 AU	"a" similar to Trojans West, but the asteroid is far from Point L5
52007 2002 EQ47	a = 4.262 AU	Q = 5.208 AU
NB: 37384 2001 WU1 with Q = 4.9295 AU does not cross Jupiter's orbit.
JUPITER-TROJANS
The Jupiter-Trojans form two populations of isolated objects, at the L4 and L5 Lagrangian points, 60° preceding and following Jupiter in its orbit.
They are placed in a very stable zone.
Levison et al. have estimated that around 2 million asteroids greater than one kilometer in size could be found at Jupiter's L4 and L5 points.
The two Trojan groups situated at the L4 and L5 Lagrangian points are not alike :
The L4 group of Trojans-East are larger in number than those of the Trojans-West near Point L5 ( 1039 for Point L4 compared to 628 for Point L5 ).
The dynamic families are more numerous for Point L4.
Of the larger asteroids, for Point L4 there are : 93 of mag H < 10 compared with only 56 for Point L5.
Orbits are more inclined for Point L5 ( 14.7° against 11.4° for Point L4)
Trojan Families having more than 10 members arising from collisions:
Melenaus	41 members in 2001	Lagrangian Point L4
Epeios	30 members in 2001	Lagrangian Point L4
Podalirius	22 members in 2001	Lagrangian Point L4	ex-(4086) 1986 WD
Oysseus	15 members in 2001	Lagrangian Point L4
(5119) 1988 RA1	23 members in 2001	Lagrangian Point L5
On average, collisions would have been more numerous for the Trojans than for the Belt N°1.  Consequently, the lightcurve amplitudes are
higher on average.
Numbered "external Jupiter-crossers" with a > a of Jupiter and q > Q of Mars from the 85117 numbered asteroids
944 Hidalgo	a = 5.746 AU	q = 1.950 AU	H = 10.77
15504 1999 RG33	a = 9.390 AU	q = 2.140 AU	H = 12.1
20461 Dioretsa	a = 23.759 AU	q = 2.386 AU	H = 13.8	1999 LD31
37117 2000 VU2	a = 6.924 AU	q = 3.092 AU	H = 13.2
65407 2002 RP120	a = 56.094 AU	q = 2.473 AU	H = 12.3
Personal remark:
External Jupiter-crossers are not named "Centaurs" but their semi-major axes "a" are similarly situated between Jupiter and Neptune.
It is only the Centaurs that have high eccentricity …..
CENTAURS
Centaurs have orbits entirely between those of Jupiter and Neptune, in a zone where - due to strong planetary perturbations - the orbits are very
chaotic ( lifetimes of less than 10 million years ).
The region between Jupiter and Saturn is virtually empty, owing to perturbations from these two giant planets, similarly for the region between Uranus and Neptune.
Save for two narrow zones at 7.02 and 7.54 AU and a zone situated between 24 and 27 AU, in which an orbit having very low "e" and  "i" can remain stable, only
a few resonance zones can be temporarily occupied.
The majority of them are situated beyond the orbit of Saturn in a region some 24 to 27 AU from the Sun.
Centaurs may be objects derived from the Kuiper Belt  in transit towards the inner Solar System, prior to becoming, probably, short-period comets.
Some of them stay trapped in resonances linked to a single giant planet during about 1,000 to 10,000 years.
Those resonances involving two or three planets at a time can hold them for even longer, more than 100,000 years.
There may exist more than 10 million Centaurs greater than 2 km in diameter, of which a hundred may exceed 100 km in diameter.
30 to 40% of them do not migrate towards the inner Solar System on cometary orbits
These could end up in the region of the Hildas (2:3 resonance with Jupiter) or the Griquas (1:2 resonance with Jupiter).
10199 Chariklo is the largest Centaur known to date ( 273 to 302 km in diameter ).  Water has been detected on its surface.
2060 Chiron, the first Centaur discovered in 1977, is also considered to be cometary ( 95P/Chiron ).
Its cometary activity has been recognised since the end of 1987, at which time a surprising increase in its H magnitude was noted.
By contrast, the comet C/2000 B4 LINEAR, which is present amongst the Centaurs, has become inactive. If it had been discovered later on then it would have been classed
as a Centaur.
Other than Chiron, 7 comets are known having Centaur-like orbital characteristics :
Comets with Centaure orbits		q in AU	a in AU		Q in AU
29P/Schwassmann-Wachmann 1		5,721	5,992		6,263
39P/Oterma		5,471	7,242		9,013
1986XIV-Shoemaker		5,457	5.473		5.489
P/1997 T3 Carsenty-Nathues		6,846	11,264		15,681
C/2001 T4 NEAT		8,555	14,140		19,724
C/2000 B4 LINEAR		6,819	18,123		29,428
C/2001 M10 NEAT		5,298	26,710		48,123
P/2004 A1 LONEOS		5,463	7,896		10,330
NEPTUNE-TROJANS
If, from strong initial perturbations, Saturn-Trojans and those of Uranus have not been able to survive at the relevant Lagrangian points, those of Neptune
must in part have been able to do so.
50% of Neptune-Trojans could still remain at the Lagrangian points of Neptune, that is 6,000 to 17,000 objects of mag V = 22 ( d = 110 km ) to V = 25 ( d = 30 km ).
One sole Neptune-Trojan is known to date.  Discovered in 2001, it has been confirmed during early 2003 :
2001 QR322	H = 7.3  ( Diam ~ 160 Km )	a = 30.1138 AU	e = 0.025	i = 1.327°
TRANS-NEPTUNIANS
Apart from Pluto found in 1930, the second trans-Neptunian discovered was 1992 QB1 (Asteroid 15760), in January 1992.
In spite of observational difficulties, more than 850 TNOs have been discovered as of the end of 2003, but a lot of these have been lost after being followed for a short time.
About half of known TNOs have been observed for less than 6 months, which is less than 1% of their orbit, the semi-major axis of which can be in error by dozens of AU !
Even the most well-known TNOs have travelled only a small part of their orbit since their discovery or since identification on old photographic plates.
( Pluto 35% of its orbit and 20000 Varuna 16% ).
Therefore we still do not have very precise data for the new Kuiper Belt and its members, given that the current means of observation allows one to hardly go beyond 50 AU.
Only large objects orbiting or reaching their perihelion within this distance can currently be found.
Nevertheless, two large populations have been discerned that is to say the Plutinos having orbits similar to the largest amongst them, Pluto, and a population of objects
near 42 AU which does not transect the orbit of Neptune.
1992 QB1, an object of the 2nd type, takes its "phonetic" pronunciation from the group called "Cubewanos".
This group could be made up of two dynamically-distinct populations, which are differentiated by their inclinations and absolute magnitudes.
Over 12 years, the accumulation of discoveries has enabled us to have a better idea of the structure of the Kuiper Belt.
There exists a small population of objects for which the semi-major axis is situated between Neptune (a = 30 AU) and the Plutinos (a = 39 AU).
It seems that this "inner" zone between 30 and 38 AU must be occupied by those TNOs separated by the 5:4 resonance ( a = 35.0 AU )
Between 30 and 35 AU, there is a population of objects having high eccentricities, which often leads them in the vicinity of the orbit of Uranus near 20 AU.
Between 36 and 39 AU, one has principally TNOs with low eccentricities that do not traverse Neptune's orbit and which are close to or in the zone of
the 4:3 resonance ( a = 36.6 AU )
In my table, I have therefore named these two zones "KBO Inner I" and "KBO Inner II".
Coming now to the Plutinos ( a ~ 39 AU ) and Pluto.  They are trapped in the 2:3 resonance with the mean motion of Neptune and often cross the orbit of
the planet near their perihelia, but never approaching the planet itself.  Pluto never gets nearer than 17 AU to Neptune.
A large number of secular and mean motion resonances exist in the zone occupied by TNOs, and these impart a complex structure to the Transneptunian Belt between
39 and 41 AU. This region between the Plutinos and 41 AU is not well-populated.
The Belt of the Classical Cubewanos", also named "CKBOs" (Classical Kuiper Belt Objects) by Jewitt, occupies a region comprising between a = 40 to 47 AU.
The Cubewanos do not intersect the orbit of Neptune and have low eccentricities and inclinations.  They are in a very gravitationally-stable part of the Solar System.
(50000) Quaoar is the largest TNO presently found in the CKBO belt.
A third group of TNOs having high eccentricity with a semi-major axis located beyond 50 AU, has now been found.
This is the SDO (Scattered Disk Object) with perihelia less than or close to 40 AU and subject to the influence of Neptune.
The origin of this group seems to have been through the external migration of Neptune at the beginning of the Solar System. The orbits of SDOs would have become very elliptical.
Only beyond the KBO objects of large eccentricity in the 5:3, 7:4 and 2:1 resonances, we find the beginning of the SDO or SKBO (Scattered Kuiper Belt Objects) zone
of which we can currently discover only those objects having large eccentricities with their perihelia within 50 AU.
Kuiper-belt objects should be composed of ices of H2O, CO and CO2 together with dust, and should be the origin of the short-period comets.
Certain TNOs are susceptible to cometary activity such as the SKBO (29981) 1999 TD10 when close to perihelion.
One estimate dating from 2000 put forward the possible existence of 800 million objects greater than 5 km in diameter.
Yet, between 90 to 99% of the initial mass in the trans-Neptunian zone would have been lost following perturbations by Neptune and the many collisions between
the innumerable initial TNOs.
However,a search for small TNOs carried out with the Hubble satellite found only 3 small TNOs of 25 to 45 km in diameter (mag 26 to 28), when 60 small TNOs were expected
in the studied zone. This lack of small TNOs has not yet been explained.
One more recent estimates made at Kitt Peak National Observatory ( MPML 29-May-02 ) put forward the existence of 34 objects of the size of Charon and 4 of the size of
Pluto, which are yet to be discovered in the Kuiper Belt. These as-yet-undiscovered objects would be very faint and therefore distant ….
According to a very recent hypothesis of 2003, it could be that the current Kuiper Belt has been formed from objects repelled by Neptune at the time of its outer
initial migration, rather than from the presence of a proto-planetary disk beyond 30 AU.
Mean-motion resonances of TNOs with Neptune:
Main Resonances	Solar Distance	Currently numbered TNOs	Currently unnumbered TNOs	Remarks
Resonance 5:4	a ~ 35.1 AU		1999 CP133, 2003 FC128, 2002 GW32
Resonance 4:3	a ~ 36.6 AU	(15836) 1995 DA2	2000CQ104, 1998 UU43	Inner zone of the Kuiper Belt
Resonance 7:5	a ~ 37.7 AU	(42355) 2002 XW93 ?	2002 XW93 ?	Region empty of TNOs ?
Resonance 3:2	a ~ 39.4 AU	Pluton and the Plutinos		Plutinos zone
Resonance 5:3	a ~ 42.1 AU	(59358) 1999 CL158, (15809) 1994 JS and 2002 VA131, amongst others
Resonance 7:4	a ~ 43.8 AU	(60620) 2000 FD8	2000 OP67, 1999 KR18
Resonance 9:5	a ~ 44.6 AU		2000 QM51 ?
Resonance 2:1	a ~ 47.8 AU	(40314) 1999 KR76, (20161) 1996 TR66, (26308) 1998 SM165, 1997 SZ10, amongst others
Resonance 5:2	a ~ 55 AU	(26375) 1999 DE9, (38084) 1999 HB12, (60621) 2000 FE8, amongst others
Resonance 11:2	a ~ 92 AU
Resonance 15:2	a ~ 115 AU
The actual or possible presence of TNOs in the resonances 1:1, 5:4, 4:3, 3:2, 5:3, 7:4, 9:5, 2:1 and 5:2 has recently been confirmed on the basis of theoretical calculation.
Save for the Neptune-Trojans (resonance 1:1), those TNOs in resonances are all of high orbital eccentricity or inclination.
NB: There are several secular resonances present which cross the inner resonances of the Kuiper Belt.
PLUTO = Major Planet or big Asteroid ?
Pluto is twice as small as the other solid planets located very close to the Sun
Pluto crosses the orbit of another Giant Planet and is in a 2:3 resonance with it, and thus remains under its influence.
Its diameter is less than that of many natural satellites such as the Moon.
Its orbit is similar to those of the very numerous trans-Neptunians "controlled" by Neptune.
Its round shape and (likely) internal differentiation already exist for the largest asteroids.
Some satellites notably Titan have an atmosphere thicker than that of Pluto.
Other asteroids possess their own satellite, such as the Earth-crosser 69230 Hermes, 243 Ida in the Belt N°1, the Kuiper object 1998 WW31, etc....
A comparative table of main data shows the great difference between the inner planets and the three biggest TNOs :
	EARTH  VENUS    MARS     MERCURY    PLUTO      SEDNA   2004 DW
Mass	1           0.81         0.11          0.06            0.0017           ?              ?
Diameter in Km	12742    12104     6792         4879            2300        1600?      1300?
Density in d/cm3	5.515       5.24       3.94           5.43              2.05             ?             ?
Orbit shaped by :	Sun        Sun        Sun          Sun            Neptune       Sun       Neptune
	+  Sun                         + Sun
Continuing to include Pluto as one of the Large Planets which shape their own environment seems at present to be a little daring ….
There is nothing which distinguishes Pluto from the other Plutinos with the exception of its size as the largest TNO currently known.
Some yet-unknown objects in the Kuiper Belt may perhaps also be as big as Pluto ?
In comparison to Ceres, which was rightly relegated from its position as a "Planet" after 45 to 50 years during the 19th Century, Pluto in proportion
is hardly much bigger than the plutino 2004 DW in relation to what Ceres is towards the other very large asteroids of the Belt N°1.
To relegate Pluto from its status as a Major Planet would take nothing away from its title as the largest Plutino nor from the credit of the discoverer, Clyde Tombaugh.
One might also claim that there is an injustice at present concerning Giuseppe Piazzi, discoverer of 1 Ceres, the largest main-belt asteroid ...
It is still regrettable that an out-moded chauvinism can at present get the upper hand over a scientific fact accepted by the majority of the International
Astronomical Community.
The inclusion of definitively-numbered objects also allows less room for distorting the statistics, work and analyses done on these objects …
The N° 100000, if assigned to Pluto, would allow one at last to honour the largest and most exceptional double asteroid, that is the Pluto-Charon system.
EXISTENCE OF A DIFFUSE DISK EXTENDING BEYOND 50 AU ?
Beyond 50 AU from the Sun, the Astronomical Community is largely reduced to making suppositions concerning the most distant regions of the Kuiper Belt.
The apparent absence of TNOs having near-circular orbits beyond 47 AU could be a sign that a massive body is situated beyond 50 AU.
With a quite low eccentricity, it may be in a very inclined orbit, and therefore has not been found to date.
This massive body some 2000 to 4000 km in diameter could be orbiting on average some 62 AU from the Sun, with q = 49 AU, Q = 78 AU and e = 0.21.
Its visual magnitude would be between +18.5 and +21.5 for the case having an albedo of 0.04, or +16.2 to +19.7 if having a high albedo of 0.3.
The outer limit of the Kuiper zone is still not known, but up until 2003 has been considered to be about 200 AU from the Sun.
Dust disks around other nearby solar-type stars can extend between 35 AU and 75 AU in the case of 'Epsilon Eridani, being a billion years old,
to 1000 AU for very young stars like Beta Pictoris. The residual disk around the Sun should certainly tend in size towards that of Epsilon Eridani.
A study in 2001 by B.Gladman et al. looked to prove the existence of an Extended Scattered Disk, which could contain at least 10,000 "SDOs" greater than
100 km, and even more than in the SKBO zone, with high "a" and "q" > 40 AU.
(48639) 1995 TL8, 2000 CR105, as well as a number of unrecovered KBOs should be members of this Extended Scattered Disk.
Those objects observed to date over less than 2% of their orbit have been very difficult to discover and authenticate over time as being members of this Extended Scattered Disk.
The massive object named 2003 VB12 ( alias "Sedna" ) discovered in November 2003 could also be a member of this extended diffuse disk
2000 CR105 and 2003 VB12 are the only objects currently known orbiting well away from the gravitational influence of Neptune.
2003 VB12 is the most massive TNO known after Pluto and is characterised by an elliptical orbit well removed from the major planets.
	q = 76.067 AU	a = 509 AU	Q = 942 AU
The origin of its current orbit is not evident, although at present there is a tendency towards the idea of a passing star approaching to about 800 AU of the Sun.
This star could have ejected 2003 VB12 and the ESDOs from the TNO zone, soonafter the formation of the Solar System ( A.Morbidelli and H.Levison )
Very distant asteroids with "a" = 100 AU and + ( as of 20/05/04)
Objects	H	a in AU	Period in years	q in AU	Q in AU	e
1999 RZ215	7.8	100.319	1004.8	30.959	169.680	0.691
(65489) 2003 FX128	6.3	103.530	1053.4	17.822	189.238	0.827
1999 DP8	8.9	116,000	1249.4	34.741	197,000	0.700
1999 CZ118	7.9	117.151	1268.0	37.732	196.571	0.677
1999 RD215	7.5	121.088	1332.5	37.598	204.578	0.689
(54520) 2000 PJ30	8.0	121.767	1343.7	28.531	215.002	0.765
2002 GB32	7,4	216.909	3194.6	35.361	398.457	0,836
(82158) 2001 FP185	6,1	227.133	3423.1	34.253	412.889	0,849
2000 CR105	6,1	228.582	3455.9	44.275	420.013	0,806
1996 PW	14,0	265.479	4325,6	2.541	528.418	0,990
2003 VB12	1,6	509.107	11487.2	76.066	942.147	0,850
2000 OO67	9,1	518.538	11807.9	20.764	1016.312	0,959
NB: 1996 PW has a cometary-like orbit; yet it will have been recognised as an asteroid so long as it did not exhibit cometary activity.
This was the case for example for 2002 VQ94 ( a = 205 AU ) which has become the comet C/2002 VQ94.
Personal comment : If the first 2 of the 12 distant asteroids orbiting at more than 100 AU from the Sun are regarded as being associated with the SDO group between
50 AU to 104 AU, there appears to remain 3 concentrations for 9 of the 10 more-distant objects, namely :
	1) A group of 4 objects between 116 and 122 AU, perhaps linked to the 15:2 resonance with Neptune, located near 115 AU
	2) 3 objects between 217 and 227 AU : 2002 GB32, 2000 CR105 and (82158) 2001 FP185
	3) A pair situated towards 515 AU, made up of 2003 VB12 and 2000 OO67
	The successive differences between the SDOs and these 3 concentrations seems to correspond to about 8, 95 and 282 AU, respectively.
	The only isolated and distant asteroid is the "Damocloid" 1996 PW which has above all a cometary orbit and has a very small diameter.
	The 65 comets known with a semi-major axis between 104 and 530 AU appear to be related to one or other of these 3 concentrations.
	Respectively 2, 4 and 1 comets are in the areas of the three groupings of asteroids.
	La comète orbiting at the same distance than 2003 VB12 and 2000 OO67 is C/1948X Bester, with a = 509.168 AU
	The orbits of all these very distant objects are still imprecise and so any possible groupings need to be considered tentative at present
	May be the future discoveries will change the aspect of these actual concentrations.
THE OORT CLOUD
The inner limit of the Oort Cloud is believed to be located between 2000 and 3000 AU.
To date, no asteroid having a semi-major axis of 2000 AU or more has been found.
2003 WT42, with a = 5840 AU and P = 158,028 years, would have been aa "Oort" asteroid, if a weak cometary activity had not been detected in January 2004.
Its staus has therefore now been changed, having become the comet C/2003 WT42.
It has however been noted that its cometary activity is quite feeble for a comet arising from the Oort Cloud.
It could therefore instead be an asteroidal body ejected from the inner Solar System very early on in it's formation.
Furthermore, it is not impossible that 2003 VB12 and 2000 CR105 could have been in fact ejected from the Oort Cloud, following a close approach by a passing star,
which perturbed them causing them to approach the inner Solar System. 2003 VB12 pourrait donc être un membre du "Nuage d'Oort interne".
Lastly, there could exist here in the inner Solar System some objects that also could have originated in the Oort Cloud : the Damocloids.
The Damocloids :
Asteroids having this unofficial name have characteristics including a very high eccentricity and/or a very high orbital inclination, which
most probably have their origin in the Oort Cloud.  The present list is that of Brian Skiff's, and covers those asteroids having as characteristics :
q < 5.2 AU, e > 0.7 and i high and/or retrograde  :
5335 Damocles	a = 11.831 AU	H  = 13.3	e = 0.867  and   i = 62.1°	q = 1.572 AU		Q = 22.091 AU
(15504) 1999 RG33	a = 9.390 AU	H  = 12.1	e = 0.772  and   i = 34.9°	q = 2.140 AU		Q = 16.641 AU
20461 Dioretsa	a = 23.759 AU	H  = 13.8	e = 0.899  and   i = 160.3°	q = 2.386 AU		Q = 45.131 AU
(65407) 2002 RP 120	a = 56.094 AU	H  = 12.3	e = 0.955  and   i = 119.1°	q = 2.473 AU		Q = 109.714 AU
1996 PW	a = 265.4 AU	H  = 14.0	e = 0.990  and   i = 29.7°	q = 2.541 AU		Q = 528.4 AU
1997 MD10	a = 26.581 AU	H  = 16.0	e = 0.941  and   i = 59.0°	q = 1.545 AU		Q = 51.618 AU
1998 QJ1	a = 11.274 AU	H  = 16.5	e = 0.812  and   i = 23.4°	q = 2.109 AU		Q = 20.439 AU
1998 WU24	a = 15.216 AU	H  = 15.0	e = 0.906  and   i = 42.5°	q = 1.425 AU		Q = 29.006 AU
1999 LE31	a = 8.128 AU	H  = 12.4	e = 0.469  and   i = 151.8°	q = 4.315 AU		Q = 11.954 AU
1999 XS35	a = 17.945 AU	H  = 17.2	e = 0.946  and   i = 19.4°	q = 0.946 AU		Q = 34.937 AU
2000 AB229	a = 53.066 AU	H  = 14.0	e = 0.956  and   i = 68.7°	q = 2.297 AU		Q = 103.8 AU
2000 DG8	a = 10.804 AU	H  = 13.1	e = 0.793  and   i = 129.4°	q = 2.229 AU		Q = 19.378 AU
2000 HE46	a = 23.597 AU	H  = 14.8	e = 0.900  and   i = 158.4°	q = 2.359 AU		Q = 44.835 AU
2000 KP65	a = 88.737 AU	H  = 10.5	e = 0.963  and   i = 45.6°	q = 3.274 AU		Q = 174.2 AU
2001 QF6	a = 7.248 AU	H  = 15.4	e = 0.688  and   i = 24.2°	q = 2.255 AU		Q = 12.240 AU
2003 UY283	a = 33.453 AU	H  = 15.3	e = 0.895  and   i = 18.8°	q = 3.506 AU		Q = 63.401 AU
Personal remark : This list cannot be exhaustive, even for found objects, as certain Damocloids can have a low inclination.
For example, this could be the case for 2004 CM111 ( q = 4.942 AU, a = 33.180 AU, e = 0.851 but with i = 4.7° )
2001 QF6 and 1999 LE31 are under the excentricity required, while the asteroids below are not included :
3552 Don Quixote	a = 4.231 AU	H  = 13.0	e = 0.712  et   i = 30.8°	q = 1,215 AU		Q = 7.247 AU
2003 WN188	a = 14.567 AU	H  = 14.1	e = 0.849  et   i = 26.9°	q = 2,199 AU		Q = 26.935 AU
DATA AND STATISTICS RELATING TO THE MINOR PLANETS
Various absolute records as of 20-May-04 from the 214014 minor planets
TYPE	ASTEROID	RECORD	ASTEROID GROUP
q minimum	2000 BD19	0.0919 AU	ATEN
q maximum	2003 VB12	76.066 UA	ESDO ?
a minimum	2004 JG6	0.6332 UA	APOHELE
a maximum	2000 OO67	518.5 AU	OORT ?
Q minimum	2004 JG6	0.9723 UA	APOHELE
Q maximum	2000 OO67	1016.3 UA	SDO ?
P minimum	2004 JG6	184.4 days	APOHELE
P maximum	2000 OO67	11808 years	ESDO ?
e minimum	2002 XR24	e = 0.0001293	BELT N°1
e maximum	1996 PW	e = 0.959	SDO ?
H max known	2003 SQ222	H=30.1 (about 4 meters)	APOLLO 1
H min - Belt N°1	(4) Vesta	3.20	BELT N°1
Largest - Belt N°1	(1) Ceres	933 km (diameter)	BELT N°1
H min - TNO	Pluton and 2003 VB12 (Sedna)	-1.1 and +1.6	PLUTINO et ESDO
i minimum	2004 FH	i = 0.02081°	ATEN
i maximum	(20461) Dioretsa	i = 160.3955°	JUPITER-CROSSER
rotation minimum	2000 DO8	Period = 1.3038 min	APOLLO-3
rotation maximum	(288) Glauke	Period  = 1200 h	BELT N°1
V Ampl. minimum	(1) Ceres	0.04 magnitude	BELT N°1
V Ampl. maximum	1865 Cerberus	2.10 magnitude	APOLLO-1
Min.Dist.from Earth - seen	2004 FH	0.00033 AU ( 49367 Km)	(18.9/03/2004) ATEN ( H =25.7 )
(as of 20-May-04)	2003 SQ222	0,00056 AU (83774Km)	(27.9/09/2003) APOLLO-1 ( H = 30,1 )
	1994 XM1	0,00072 AU (107700Km)	(09.8/12/1994) APOLLO-2 ( H = 28,0 )
Min.Dist.from Earth - pred.	2000 SB45	0.00142 AU (212400 km)	(07.8/10/2037)  APOLLO 2 ( H = 24.5 )
for the future	2001 WN5	0.00167 AU (249800 km)	(26.2/06/2028) APOLLO 2 ( H = 18.3 )
(as of 20-May-04)	1999 AN10	0.00265 AU (396000 km)	(07.3/08/2027) APOLLO 1 ( H = 17.1 )
( prior to 2037 )	2003 MK4	0.00507 AU  (758400 km)	(03.9/01/2032) APOLLO 1 ( H = 21.0 )
NB: The asteroid observed closest to the Earth was in fact the "Montana Bolide", which in 1972, skimmed the Earth's upper atmosphere reaching a minimum
altitude of 58 km, and much of which was consumed before returning to space.
Orbit prior to encounter :	a = 1.661 AU	e = 0.3904	q = 1.0127 AU	i = 15.22°		Amor 2
Orbit after encounter :	a = 1.471 AU	e = 0.3633	q = 0.9369 AU	i = 6.92°		Apollo 1
NB: The minimum V amplitude is taken from those lightcurves, which we know are complete.
Various records by Group as of 31-Dec-03 for the 203614 asteroids and for the 73606 numbered ones only
Groups / Limits "a"	"a" min	"a" max	Object "a" min. // Object "a" max.	Numbered, "a" min.		Numbered, "a" max.
Apohele	0.693 AU	0.741 AU	2003 CP20 // 1998 DK36	-	-	-	-
Aten	0.642 AU	0.9988 AU	(66391) 1999 KW4 // 1998 UP1	66391	0.642 AU	3753	0.997 AU
Apollo	1.0006 AU	17.945 AU	(54509) 2000 PH5 // 1999 XS35	54509	1.0006 AU	14827	2.846 AU
Amor	1.034 AU	4.232 AU	1992 JD // (3552) Don Quixote	66407	1.198 AU	3552	4.232 AU
Mars-crosser	1.390 AU	26.581 AU	(1951) Lick // 1997 MD10	1951	1.390 AU	5335	11.831 AU
Hungaria	1.768 AU	2.098 AU	2002 JA14 // 2002 QZ5	45873	1.768 AU	54420	2.055 AU
Belt N°1 (a < Cybeles)	2.0662 AU	3.2914 AU	2003 SH241 // 2003 YK69	59039	2.1009 AU	11097	3.2798 AU
Cybele	3.283 AU	3.673 AU	2003 BS48 // 2003 KB11	14871	3.284 AU	13096	3.654 AU
Hilda	3.745 AU	4.022 AU	2002 TB96 // 2003 QY103	70032	3.748 AU	17305	4.019 AU
Jupiter-Trojan East	4.906 AU	5.385 AU	1997 TW2 // 2003 FH103	63176	5.050 AU	22049	5.367 AU
Jupiter-Trojan West	4.961 AU	5.361 AU	2000 HR24 // (34835) 2001 SZ249	24454	5.062 AU	34835	5.361 AU
Jupiter-crosser	3.349 AU	88.737 AU	2002 LJ27 // 2000 KP65	5164	3.645 AU	65407	56.094 AU
Centaur	7.883 AU	28.968 AU	2000 GM137 // 2002 FY36	52872	8.404 AU	52975	26.209 AU
Inner KBO	30.229 AU	38.955 AU	2001 XA255 // 1998 WV24	73480	30.743 AU	42355	38.383 AU
Plutino	38.769 AU	40.149 AU	2003 FF128 // 2000 YH2	38083	39.207 AU	38628	39.607 AU
Cubewano + KBO 2:1	40.308 AU	48.067 AU	1999 OH4 // (40314) 1999 KR16	24835	41.804 AU	40314	48.986 AU
SDO	49.041 AU	121.767 AU	2000 AF255 // (54520) 2000 PJ30	60608	49.996 AU	54520	121.767 AU
Oort ?	265.480 AU	518.538 AU	1996 PW // 2000 OO67	-	-	-	-
NB: The limits in "a" indicated are established only after the fact that the object's membership of a group is assured.
Group / H mag range	Minimum H	Maximum H	Remarks
Apohele	16.5  ( 2003 CP20 )	25.0 ( 1998 DK36 ? )
Aten	14.5       ( 1999 HF1 )	29.1   ( 2003 SW130 )
Apollo	13.0   ( 1866 Sisyphus )	30.1   ( 2003 SQ222 )
Amor	9.45  ( 1036 Ganymed )	27.6  ( 2001 UD18 )	only one large Amor 1 : 433 Eros ( H = 11.2 ), followed by 1943 Anteros ( H = 15.8 )
Mars-crosser	9.38      ( 132 Aethra )	22.8   ( 2002 NU16 )
Mars-Trojan	16.1    ( 5261 Eureka ? )	21.3  ( 2001 FG24 ? )
Hungaria	11.21  ( 434 Hungaria )	20.6 ( 2003 HE2 )	2003 HE2     : q = 1.777 AU  a = 2.038 AU and e = 0.127
Belt N°1	3.20    (4 Vesta )	20.9  (2003 SV100)	2003 SV100 : q = 1.679 AU  a = 3.486 AU and e = 0.349
Cybele	6.6     ( 65 Cybele )	19.5 ( 2002 JE109 )	2002 JE109  : q = 1.676 AU  a = 3.322 AU and e = 0.495
Hilda	7.5     ( 153 Hilda )	17.9 ( 2002 UP36 )	2002 UP36   : q = 2.125 AU  a = 3.890 AU and e = 0.453
Jupiter-Trojan East	7.49    ( 624 Hektor )	15.4  ( 2002 AT14 )	2002 AT14   : q = 3.624 AU  a = 5.148 AU and e = 0.296
Jupiter-Trojan West	8.1    ( 3451 Mentor )	15.1 ( 2000 QV233 )	2000 QV233 : q = 3.859 AU  a = 5.132 AU and e = 0.248
Centaur	6.0    ( 1995 SN55 )	14.3  ( 2000 GM37 )	2000 GM137 : q = 6.927 AU  a = 7.883 AU and e = 0.121
Inner KBO	4.5  ( 2002 KX14 )	9.3  ( 1996 AS20 )	1996 AS20  : q = 13.565 AU  a = 35.787 AU and e = 0.621
Plutino	- 1.1      ( Pluto )	12.4  ( 1999 DA8 )	1997 DA8    : q = 26.401 AU  a = 39.316 AU and e = 0.329
Cubewano	2.6   ( 50000 Quaoar )	11.9  ( 2003 BH91 )	low e
SDO	3,9    ( 2000 TC302 )	14.1  ( 2003 QM12 )	2003 QM112 : q = 13.169 AU  a = 83.397 AU et e = 0.842
Oort ?	9.1     (2000 OO67 )	14.0  ( 1996 PW )	very high e
Remarks:
* Definitive records are shown in "bold".
* The minimum H magnitude reached for each group is often for objects having high eccentricities or by those close to the inner edge of the zone.
The H magnitude limit reached by asteroids of intermediate or low eccentricity are relatively less bright.
* The largest asteroids not definitively associated with the Belt N°1 ( inner, central or outer zone ) and found up until 2003 (given that there has not been
a large error in the H magnitude, something which is currently still fairly frequent ) are of the following H magnitudes :
	Period 1951 to 2001	Period 2001 to 2003
Inner Zone	13.3	13.6
Central Zone	12.4	13.1
Outer Zone	12.1	12.8
The largest asteroids having H mag < 5.0 listed in order of H magnitude ( as of 20-May-04 ) :
NAME	PROVISIONAL NAME	MAGNITUDE H	DIAM. actual or (estimated) in km	GROUP	ALBEDO
Pluto	-	- 1.1	2262 to 2320	Plutino	60%
(Charon)	-	+ 0.9	1270	Plutino	40%
Sedna ?	2003 VB12	+ 1.6	1600 ?	ESDO ?	>13%
-	2004 DW	+ 2.4		Plutino
50000 Quaoar	2002 LM60	+ 2.6	1250 +/-50 (Brown / Trujillo - HST)	Cubewano	12%
4 Vesta	-	+ 3.20	530	Belt N°1	38%
28978 Ixion	2001 KX76	+ 3.2	1055 +/-165 ( Bertoldi et al. - IRAM )	Plutino	9%
55565 2002 AW197	2002 AW197	+ 3.3	890 +/-120 ( Margot et al - IRAM )	SDO	10%
55636 2002 TX300	2002 TX300	+ 3.3		Cubewano
1 Ceres	-	+ 3.34	950 +/- 8   ( Stern et al. - HST )	Belt N°1	10%
55637 2002 UX25	2002 UX25	+ 3.6		Cubewano
20000 Varuna	2000 WR106	+ 3.7	900 +/-140 ( D.Jewitt - JCMT )	Cubewano	7%
-	2002 MS4	+ 3.9		Cubewano
(84522) 2002 TC302	2002 TC302	+ 3.9		SDO
-	2004 GV9	+ 3.9		Cubewano
-	2003 AZ84	+ 4.0		Plutino
2 Pallas	-	+ 4.13	498	Belt N°1	14%
42301 2001 UR163	2001 UR163	+ 4.2		SDO
-	2003 QM91	+ 4.2		Cubewano
(84922) 2003 VS2	2003 VS2	+ 4.2		Plutino
19308 1996 TO66	1996 TO66	+ 4.5	(709)  (in 2000 by Gil-Hutton)	Cubewano
-	2002 KX14	+ 4.5		Inner KBO II
-	2003 QW90	+ 4.5		Cubewano
26375 1999 DE9	1999 DE9	+ 4.7		SDO 5:2
38628 Huya	2000 EB173	+ 4.7	(696 with H=+5.09) (Barucci et al)	Plutino	4%
-	2001 QF298	+ 4.7		Plutino
-	2002 WC19	+ 4.7		KBO 2:1
24835 1995 SM55	1995 SM55	+ 4.8	(813) (in 2000 by Gil-Hutton)	Cubewano
-	2003 FY128	+ 4.8		SDO
19521 Chaos	1998 WH24	+ 4.9		Cubewano
47171 1999 TC36	1999 TC36	+ 4.9	675 +/-100 ( Bertholdi et al - IRAM )	Plutino	3.5%
-	2002 CY248	+ 4.9		Cubewano
NB: Main-belt asteroids ( Mars to Jupiter) in red and asteroids from Belt N°2 (TNOs) in black
There are 3 large asteroids in the Belt N°1 compared with 26 for Belt N°2.  The Principal Belt is no longer that which one used to believe…
The smallest asteroids ( as of 25-May-04 ) :
Numbered asteroids	= Mag H 22.7 for	(54509) 2000 PH5 (Ap.1)	(65717) 1993 BX3 (H = 21.0 /Am.3 )	(41429) 2000 GE2 ( 20.7 /Ap.2)
Unnumbered asteroids	= Mag H 30.1 for	2003 SQ222 (Apollo 1)	2003 YS70 (H=29.2 /Ap.1)	2003 SW130 (H= 29.1 /Aten)
On 26 October 1995, the Spacewatch Telescope observed an asteroid named "SS-291" of 2 to 4 meters in diameter ( H = 31.0 )  (source MPML 25-Oct-02)
An unconfirmed suspect estimated to be of mag H 30.6 and named "P00ACE", was observed by LONEOS on the 28th and 29th September 2003 of the
Apollo 1 type ( a = 1.408 AU and e = 0.474 ), it would have been between 2-5 meters across.  It passed as close as 89,800 km to Earth on 27.94 September 2003
( MPML 30-Sep-03 ).
Magnitude H = 18.2 corresponds to more or less 1 km in diameter:			Estimated number 1 km or more in size = > 5,000,000 !.. numbered =				73 636
Shortest rotational periods of the asteroids (  < 10 minutes ) known as of 05-Dec-03
2000 DO8	APOLLO 3	85x40 m across	Rotation period = 1.3038 min		H = 24.8
2000 WH10	APOLLO 3	130 m diameter	Rotation period = 1.374 min		H = 22.5
2003 EM1	ATEN	55 m diameter	Rotation period = 1.858 min		H = 24.5	(CDR+CDL website)
2003 DW10	APOLLO 1	25 m diameter	Rotation period < 2 min		H = 26.1	(MPML 08-Mar-03)
2003 EP4	APOLLO 1	70 m diameter	Rotation period ~ 2 min		H = 23.9	(MPML 13-Mar-03)
1999 SF10	APOLLO 1	60 m diameter	Rotation period = 2.466 min		H = 24.2
2001 WV1	APOLLO 1	130 m diameter	Rotation period = 2.694 min		H = 22.5
2000 UK11	ATEN	40 m diameter	Rotation period = 3 min		H = 25.3
2004 FH	ATEN	30 m diameter	Rotation period = 3.023 min		H = 25.7
2001 SQ3	APOLLO 1	200 m diameter	Rotation period = 3.75 min		H = 21.7
2000 WS28	APOLLO 2	75 m diameter	Rotation period = 4.386 min		H = 23.6
2000 AG6	APOLLO 1	80x35 m across	Rotation period = 4.598 min		H = 25.3
1999 TY2	APOLLO 3	80 m diameter	Rotation period = 7.280 min		H = 23.3
2000 WG63	AMOR 2	100 m diameter	Rotation period = 8.238 min		H = 23.2
2000 WL107	AMOR 3	50 m diameter	Rotation period = 9.654 min		H = 24.8
2000 WQ148	APOLLO 2	125 m diameter	Rotation period = 9.9 min		H = 22.7
They comprise only small asteroids, fragments from collisions between larger asteroids.
These objects must obligatorily be monolithic, in contrast to larger asteroids which must be 'rubble piles', which cannot withstand such a rapid rotation.
Only one fast-rotator is currently numbered :
(54509) 2000 PH5	APOLLO  1	125 m diameter	Rotation period = 12.172 min		H = 22.7
For larger (estimated) diameters of asteroids, we have the following records :
2000 WL10	APOLLO 3	1080 m diameter	Rotation period = 19.308 min		H = 18.0
2001 OE84	AMOR 3	900 m diameter	Rotation period = 29.2 min		H = 17.8
1335 Demoulina	Belt N°1	~ 11 km diameter	Rotation period ~ 14.4 min ? ( uncertain )		H = 12.9
The 13 asteroids currently having the longest rotation period known as of 05-Dec-03
288 Glauke	Belt N°1	1200 hr
1220 Crocus	Belt N°1 ( Eos )	737 hr
253 Mathilde	Belt N°1	417.7 hr
1998 QR52	Apollo 1	235 hr
3691 Bede	Amor 2	226.8 hr
9969 Braille	Mars-crosser	226.4 hr
38071 1999 GU3	Amor 2	216 hr
65407 2002 RP120	Damocloid	199.2 hr
16064 1999 RH27	Amor 3	178.6 hr
1481 Tubingia	Belt N°1	160 hr
2003 KP2	Apollo 3	150.7 hr
3102 Krok	Amor 3	147.8 hr
1689 Floris-Jan	Belt N°1 ( Eurynome )	145 hr
While the majority of asteroids have a single rotational axis, some small planets having a very slow rotation rate do not revolve about one axis.
Following collisions in the past, they tumble themselves, and because of this fact they are prevented from displaying a similar aspect in successive lightcurves.
They have at least two different rotation periods.
They are referred to as "Tumbling Asteroids".  The largest of them is 253 Mathilde ( diameter 53 km and principal rotation period of 17.41 days )
The most studied of the small "tumbling asteroids" is the Earth-crosser 4179 Toutatis for which the rotational axis undergoes a precessional motion giving
two rotation periods of 7.42 and 5.37 days.
Other known examples are : 1689 Floris-Jan, 3288 Seleucus, 3691 Bede, 1997 BR and 38071 1999 GU3 and of course 288 Glauke (diameter 32 km).
Distribution of the 1724 asteroid rotation periods as compiled by G.Faure as of  05-Dec-03
Period of rotation	Number of asteroids	% of total	Cumulative no. with period < x hr		Cumulative %
Less than 1 hr	33	2.0%	33		2.0%
1 to < 2 hr	8	0.5%	41		2.5%
2 to < 3 hr	92	5.7%	133		8.2%
3 to < 4 hr	98	6.1%	231		14.2%
4 to < 5 hr	129	8.0%	360		22.3%
5 to < 6 hr	142	8.8%	502		31.0%
6 to < 7 hr	141	8.7%	643		39.8%
7 to < 8 hr	123	7.6%	766		47.4%
8 to < 9 hr	117	7.2%	883		54.6%
9 to < 10 hr	91	5.6%	974		60.2%
10 to < 11 hr	76	4.7%	1050		64.9%
11 to < 12 hr	56	3.5%	1106		68.4%
12 to < 13 hr	56	3.5%	1162		71.9%
13 to < 14 hr	42	2.6%	1204		74.5%
14 to < 15 hr	43	2.7%	1247		77.1%
15 to < 16 hr	48	3.0%	1295		80.1%
16 to < 17 hr	35	2.2%	1330		82.3%
17 to < 18 hr	26	1.6%	1356		83.9%
18 to < 19 hr	26	1.6%	1382		85.5%
19 to < 20 hr	27	1.7%	1409		87.1%
20 to < 21 hr	10	0.6%	1419		87.8%
21 to < 22 hr	8	0.5%	1427		88.2%
22 to < 23 hr	7	0.4%	1434		88.7%
23 to < 24 hr	11	0.7%	1445		89.4%
More than 24 hr	172	10.6	1617		100.0%
Total	1617	100%
Very uncertain periods	107
Overall Total	1724	The 1617 known periods represent 2.2% of the 73636 numbered asteroids + 172 unnumbered others
NB: Where a range of possible periods exist for a given asteroid, the minimum period has been adopted, except where a more recent second period is
known and more certain. The ill-defined periods are those of less than 24 hours and only quoted to the nearest hour.
Asteroids having the greatest lightcurve variability ( > 1.40 mag ) as of 05-Dec-03 :
1865 Cerberus	Apollo 1	Max.  2.10 mag
1620 Geographos	Apollo 1	Max.  2.03 mag
2002 TD60	Amor 1	Max.  2.0 mag
1995 HM	Amor 1	Max.  2 mag
3485 Barucci	Hertha (Belt N°1)	Max.  1.78 mag ?	( Amplitude of only 0.19 mag assessed in 2002 => ??? )
2000 EB14	Aten	Max.  1.70 mag
3102 Krok	Amor 3	Max.  1.6 mag
38071 1999 GU3	Amor 2	Max.  1.5 mag
2002 HK12	Apollo 2	Max.  1.50 mag
433 Eros	Amor 1	Max.  1.49 mag
1742 Schaifers	Koronis (Belt N°1)	Max.  1.46 mag
NB: The Jupiter-Trojans of more than 90 km diameter appear to have a lightcurve amplitude which is on average more than that of main-belt objects
( 0.198 et 0.155 magnitude respectively)
Distribution of the 1621 maximum lightcurve amplitudes as compiled by G.Faure as of  05-Dec-03 :
Amplitude in mag	No. of asteroids	% of total	Cumulative no. with ampl < x mag		Cumulative %
Less than 0.1	122	7.6%	122		8%
0.1 to < 0.2	384	24.0%	506		32%
0.2 to < 0.3	346	21.6%	852		53%
0.3 to < 0.4	252	15.7%	1104		69%
0.4 to < 0.5	167	10.4%	1271		79%
0.5 to < 0.6	105	6.6%	1376		86%
0.6 to < 0.7	65	4.1%	1441		90%
0.7 to < 0.8	41	2.6%	1482		92%
0.8 to < 0.9	35	2.2%	1517		95%
0.9 to < 1.0	26	1.6%	1543		96%
1.0 to < 1.1	15	0.9%	1558		97%
1.1 to < 1.2	15	0.9%	1573		98%
1.2 to < 1.3	10	0.6%	1583		99%
1.3 to < 1.4	5	0.3%	1588		99%
1.4 to < 1.5	7	0.4%	1595		100%
1.5 to < 1.6	2	0.1%	1597		100%
1.6 to < 1.7	1	0.1%	1598		100%
1.7 to < 1.8	1	0.1%	1599		100%
1.8 to < 1.9	0	0.0%	1599		100%
1.9 to < 2.0	0	0.0%	1599		100%
2.0 and more	4	0.2%	1603		100%
Total	1603	100%
Uncertain amplitudes	107
Overall Total	1710	The 1710 known periods represent 2.1% of the 73636 numbered asteroids + 172 unnumbered others
NB: Where a range of possible amplitudes exist for a given asteroid, the maximum one has been adopted
Generally, it is the larger asteroids that have been studied at first, since these have been more accessible to the amateurs or to the Astronomers equipped with photometers.
It has been shown that high-amplitude lightcurves are not very numerous, at least amongst the larger asteroids.
In the context of refining or verifying to a tenth of a magnitude the H magnitudes of the minor planets, that which is interesting and should be noted :
- the expected variation is only the half-amplitude (thus at most 0.2 mag for 75% of asteroids !) either side of the H magnitude that can alter the measures in general.
- The table above summarises the maximum amplitude for each asteroid.  Each object amongst them can of cause exhit a lower amplitude.
- Finally, the elapsed time between maximum and minimum light for an asteroid is only a small part of the rotation period, so this change does not reoccur that frequently.
It follows that the intrinsic variability is often less problematic in practice, if the aim is to achieve a precision of 0.1 mag as required particularly by the MAP ( Magnitude
Alert Project ).  A good number of measurements over several oppositions and a statistical average most often results in levelling out any deviation owing to variability.
Distribution of the 206295 Asteroids by magnitude H as of 31-Dec-03 :
NB: The albedo ( % sunlight reflected ) of each asteroid varies depending on the type of surface, therefore the dimensions quoted comprise ranges of size
ABSOLUTE MAG	DIAMETER in KM	TOTAL NUMBERED	TOTAL UNNUMBERED		OVERALL TOTAL		% TOTAL
Magnitude H = -1	2280	0	1		1		0.0
Magnitude H = 1	1600	0	0		0		0.0
Magnitude H = 2	1250	1	0		1		0.0
Magnitude H = 3	420 to 1500	8	2		10		0.0
Magnitude H = 4	260 to 940	8	9		17		0.0
Magnitude H = 5	170 to 590	17	59		76		0.0
Magnitude H = 6	110 to 370	43	225		268		0.1
Magnitude H = 7	65 to 240	123	284		407		0.2
Magnitude H = 8	40 to 150	231	155		386		0.2
Magnitude H = 9	25 to 95	456	52		508		0.2
Magnitude H = 10	17 to 60	722	24		746		0.4
Magnitude H = 11	11 to 37	1923	57		1980		1.0
Magnitude H = 12	7 to 24	5262	406		5668		2.7
Magnitude H = 13	4 to 15	14603	2821		17424		8.4
Magnitude H = 14	3 to 9	24077	18903		42980		20.8
Magnitude H = 15	2 to 6	19560	42496		62056		30.1
Magnitude H = 16	1 to 4	6013	44225		50238		24.4
Magnitude H = 17	0.7 to 2	506	17705		18211		8.8
Magnitude H = 18	0.4 to 1.5	48	3265		3313		1.6
Magnitude H = 19	0.3 to 0.9	28	790		818		0.4
Magnitude H = 20	0.2 to 0.6	5	432		437		0.2
Magnitude H = 21	0.1 to 0.4	1	233		234		0.1
Magnitude H = 22	0.07 to 0.24	1	163		164		0.1
Magnitude H = 23	0.04 to 0.15	0	111		111		0.1
Magnitude H = 24	0.025 to 0.095	0	109		109		0.1
Magnitude H = 25	0.017 to 0.060	0	58		58		0.0
Magnitude H = 26	0.011 to 0.037	0	40		40		0.0
Magnitude H = 27	0.007 to 0.024	0	15		15		0.0
Magnitude H = 28	0.004 to 0.015	0	6		6		0.0
Magnitude H = 29	0.003 to 0.009	0	4		4		0.0
Magnitude H = 30	0.002 to 0.006	0	1		1		0.0
Number of asteroids concerned		73636	132651		206287		100.0
				Asteroids with unknown mag H	8
					206295
Number of asteroids per magnitude H for all-known asteroids ( numbered and unnumbered ) as of 31-Dec-03 :
Absolute	a < 4.9 AU	4.9 AU < a < 5.5 AU	5.5 AU < a < 30.6 AU	a > 30.59 AU		Overall Total
magnitudes	(  Inner asteroids )	( Jupiter-zone asteroids )	( Centaurs )	( TNO +Oort )
Mag H -1				1		1
Mag H -0						0
Mag H +0						0
Mag H +1						0
Mag H +2				1		1
Mag H +3	2			7		9
Mag H +4	1			16		17
Mag H +5	10			67		77
Mag H +6	24		4	240		268
Mag H +7	96	3	4	304		407
Mag H +8	200	22	9	155		386
Mag H +9	374	77	12	45		508
Mag H +10	584	137	11	14		746
Mag H +11	1568	400	7	5		1980
Mag H +12	5147	511	8	2		5668
Mag H +13	17024	390	10			17424
Mag H +14	42873	100	4	3		42980
Mag H +15	62049	3	3	1		62056
Mag H +16	50235	0	3			50238
Mag H +17	18208	2	1			18211
Mag H +18	3313	0	0			3313
Mag H +19	818	0	0			818
Mag H +20	437	0	0			437
Mag H +21	234	0	0			234
Mag H +22	164	0	0			164
Mag H +23	111	0	0			111
Mag H +24	109	0	0			109
Mag H +25	58	0	0			58
Mag H +26	40	0	0			40
Mag H +27	15	0	0			15
Mag H +28	6	0	0			6
Mag H +29	4	0	0			4
Mag H +30	1	0	0			1
Totaux	203705	1645	76	861		206287
				Asteroids with unknown mag H		8
				Overall Total		206295
Distribution of numbered asteroids by magnitude H for the first 85117 asteroids
Absolute	a < 4.9 AU	4.9 AU < a < 5.5 AU	5.5 AU < a < 30.6 AU	a > 30.59 AU		Overall Total
magnitudes	(  Inner asteroids )	( Jupiter-zone asteroids )	( Centaurs )	( TNO +Oort )
Mag H +2				1		1
Mag H +3	2			6		8
Mag H +4	1			8		9
Mag H +5	10			13		23
Mag H +6	24		2	22		48
Mag H +7	96	3	3	23		125
Mag H +8	200	22	1	8		231
Mag H +9	374	77	6			457
Mag H +10	584	137	3			724
Mag H +11	1568	364	2			1934
Mag H +12	5093	223	1	1		5318
Mag H +13	15281	52	3			15336
Mag H +14	27549					27549
Mag H +15	24182					24182
Mag H +16	8409					8409
Mag H +17	680					680
Mag H +18	48					48
Mag H +19	28					28
Mag H +20	5					5
Mag H +21	1					1
Mag H +22	1					1
TOTALS	84136	878	21	82		85117
Average magnitude H per thousand asteroids for the first 73000 numbered objects
1 to 999	9.6	37000 to 37999	14.8
1000 to 1999	11.6	38000 to 38999	14.7
2000 to 2999	12.4	30000 to 39999	14.9
3000 to 3999	12.7	40000 to 40999	14.8
4000 to 4999	12.8	41000 to 41999	14.7
5000 to 5999	12.9	42000 to 42999	14.7
6000 to 6999	13.2	43000 to 43999	14.7
7000 to 7999	13.5	44000 to 44999	14.9
8000 to 8999	13.7	45000 to 45999	14.5
9000 to 9999	13.9	46000 to 46999	14.8
10000 to 10999	13.9	47000 to 47999	14.6
11000 to 11999	13.9	48000 to 48999	14.9
12000 to 12999	14,0	40000 to 49999	14.8
13000 to 13999	13.8	50000 to 50999	14.7
14000 to 14999	13.9	51000 to 51999	14.4
15000 to 15999	13.8	52000 to 52999	15.1
16000 to 16999	14.1	53000 to 53999	15,0
17000 to 17999	14.1	54000 to 54999	14.8
18000 to 18999	14.3	55000 to 55999	14.8
19000 to 19999	14.3	56000 to 56999	15,0
20000 to 20999	14.3	57000 to 57999	15,0
21000 to 21999	14.5	58000 to 58999	15,0
22000 to 22999	14.5	59000 to 59999	15.3
23000 to 23999	14.4	60000 to 60999	15.5
24000 to 24999	14.4	61000 to 61999	15.5
25000 to 25999	14.4	62000 to 62999	15.2
26000 to 26999	14.5	63000 to 63999	15.3
27000 to 27999	14.3	64000 to 64999	15.6
28000 to 28999	14.3	65000 to 65999	15.5
29000 to 29999	14.2	66000 to 66999	15.2
30000 to 30999	14.4	67000 to 67999	15.4
31000 to 31999	14.3	68000 to 68999	15.4
32000 to 32999	14.3	69000 to 69999	15.3
33000 to 33999	14.6	70000 to 70999	15.4
34000 to 34999	14.5	71000 to 71999	14.9
35000 to 35999	14.8	72000 to 73000	15.2
36000 to 36999	14.7
Distribution of numbered asteroids by brightest V magnitude during the period 2003-2050 (first 73000 asteroids)
V Magnitude	a < 4.9 AU	4.9 AU < a < 5.5 AU	5.5 AU < a < 30.6 AU	a > 30.59 AU		Overall total
	(  Inner asteroids )	( Jupiter-zone asteroids )	( Centaurs )	( TNO +Oort )
Max. mag V + 5	1					1
Max. mag V + 6	3					3
Max. mag V + 7	5					5
Max. mag V + 8	20					20
Max. mag V + 9	42					42
Max. mag V + 10	120					120
Max. mag V + 11	187					187
Max. mag V + 12	373					373
Max. mag V + 13	831		1			832
Max. mag V + 14	2848	13				2861
Max. mag V + 15	9343	51	1			9395
Max. mag V + 16	20235	114	3			20352
Max. mag V + 17	24994	241	3	1		25239
Max. mag V + 18	11769	304	4	2		12079
Max. mag V + 19	1295	101	2	8		1406
Max. mag V + 20	13	10	2	7		32
Max. mag V + 21				13		13
Max. mag V + 22			3	17		20
Max. mag V + 23			1	16		17
Max. mag V + 24				3		3
Max. mag V + 25						0
TOTALS	72079	834	20	67		73000
Cumulative distribution of numbered asteroids versus limiting V magnitude for the period 2003-2050  (first 73000 asteroids)
The data below allows one to estimate the maximum number asteroids observable for a given magnitude limit depending on the equipment used
and local observing conditions :
V Mag max.observable	Cumulative no. of asteroids	V Mag max.observable	Cumulative no. of asteroids
5.0-5.4	1	14.0-14.4	2503
5.5-5.9	1	14.5-14.9	4444
6.0-6.4	1	15.0-15.4	7940
6.5-6.9	4	15.5-15.9	13838
7.0-7.4	5	16.0-16.4	22611
7.5-7.9	9	16.5-16.9	34190
8.0-8.4	17	17.0-17.4	47456
8.5-8.9	29	17.5-17.9	59429
9.0-9.4	44	18.0-18.9	71509
9.5-9.9	71	19.0-19.9	72915
10.0-10.4	118	20.0-20.9	72947
10.5-10.9	191	21.0-21.9	72960
11.0-11.4	272	22.0-22.9	72980
11.5-11.9	378	23.0-23.9	72997
12.0-12.4	530	24.0-24.9	73000
12.5-12.9	751	25.0-25.9	73000
13.0-13.4	1080
13.5-13.9	1583
Average maximum V magnitude per thousand asteroids for the first 73000 numbered objects
1 to 999	12.4	37000 to 37999	17.4
1000 to 1999	14.2	38000 to 38999	17.3
2000 to 2999	14.9	30000 to 39999	17.4
3000 to 3999	15.1	40000 to 40999	17.4
4000 to 4999	15.3	41000 to 41999	17.3
5000 to 5999	15.3	42000 to 42999	17.3
6000 to 6999	15.5	43000 to 43999	17.2
7000 to 7999	15.8	44000 to 44999	17.2
8000 to 8999	16.1	45000 to 45999	17.1
9000 to 9999	16.2	46000 to 46999	17.3
10000 to 10999	16.3	47000 to 47999	17.3
11000 to 11999	16.4	48000 to 48999	17.2
12000 to 12999	16.4	40000 to 49999	17.1
13000 to 13999	16.4	50000 to 50999	17.3
14000 to 14999	16.3	51000 to 51999	17.3
15000 to 15999	16.5	52000 to 52999	17.4
16000 to 16999	16.6	53000 to 53999	17.3
17000 to 17999	16.8	54000 to 54999	17.5
18000 to 18999	16.8	55000 to 55999	17.6
19000 to 19999	16.9	56000 to 56999	17.4
20000 to 20999	16.9	57000 to 57999	17.6
21000 to 21999	17.0	58000 to 58999	17.9
22000 to 22999	17.0	59000 to 59999	17.8
23000 to 23999	17.0	60000 to 60999	18.1
24000 to 24999	17.0	61000 to 61999	17.8
25000 to 25999	17.0	62000 to 62999	18.1
26000 to 26999	16.9	63000 to 63999	18.0
27000 to 27999	16.8	64000 to 64999	18.1
28000 to 28999	16.8	65000 to 65999	17.7
29000 to 29999	16.8	66000 to 66999	17.6
30000 to 30999	16.9	67000 to 67999	17.6
31000 to 31999	16.9	68000 to 68999	17.9
32000 to 32999	17.0	69000 to 69999	17.9
33000 to 33999	17.0	70000 to 70999	17.7
34000 to 34999	17.3	71000 to 71999	17.7
35000 to 35999	17.2	72000 to 73000	17.9
36000 to 36999	17.3
Satellites of  Asteroids observed as of 20-May-04
ASTEROID	SATELLITE NAME	DIAM.in km (#delta mag)	DISCOVERY (Reference)	"a"in km	"P"	GROUP
Pluto	Charon	1230 km	1977 - Christy (MPML 01-Apr-01)	19636	6.4 days	Plutino
22 Kalliope	Linus	ratio 1/5 (# 4.9 mag)	2001  - Merline + Margot (IAUC 7703)	1000	?
45 Eugenia	Petit-Prince	13 km (# 6.14 mag)	1998 - Merline (MPML 01-Apr-01)	1190	4.7 days
87 Sylvia	S/ 2001 (87) 1	< 10 km (# 6.5 mag)	2001 - Brown et al.# (MPML 01-Mar-01)	1200	4 days
90 Antiope	S/ 2000 (90) 1	( #  < 0.1 mag)	2000 - Merline et al. (IAUC 7503)	170	16 hr	Themis
107 Camilla	S/ 2001 (107) 1	8 km ? (# 7.0 mag)	2001 - Storrs (IAUC 7599)	0.6 arcsec	?	Cybele
121 Hermione	S/ 2002 (121) 1	13 km / Hermione = 230 km	2002 - Merline (IAUC 7980)	790	?
130 Elektra	S/ 2003 (130) 1	4 km (# 8.5 mag K)	2003 - Merline (IAUC 8183)	1170	?
243 Ida	Dactyl	1.2x1.4x1.6 km (# 6.0 mag)	1993 - Galileo probe (MPML 01-Apr-01)	85	?
283 Emma	S/ 2003 (283) 1	12 km (# 5.5 mag)	2003 - Merline (IAUC 8165)	370	?
379 Huenna	S/ 2003 (379) 1	ratio 1/13	2003 - Margot et al. (IAUC 8182)	1200	?
617 Patroclus	S/2001 (617) 1	same size (# 0.2 mag)	2001 - Merline et al. (IAUC 7741)	0.21 arcsec	?	J-Trojan
762 Pulcova	S/ 2000 (762) 1	9 km (# 4 mag)	2000 - Merline (MPML 01/04/01)	800	4 days
1509 Esclangona	S/2003 (1509) 1	4 km (# 2.4 mag K)	2003 - Merline et al. (IAUC 8075)	140	?	Hungaria
3749 Balam	S/2002 (3749) 1	7 and 1.5 km (# 0.2 mag)	2002 - Merline et al. (IAUC 7827)	?	80 days
3782 Celle	S/2003 (5381) 1	ratio 0.42	2003 - Ryan et al. (IAUC 8128)	?	36.57 hr	Vesta family
4674 Pauling	S/2004 (4674) 1	8 et 2.5 Km (# 2.5 mag K)	2004 - Merline et al (IAUC 8297)	250	?	Hungaria
5381 Sekhmet	S/2003 (5381) 1	1000 m and 300 m	2003 - Nolan (IAUC 8163)	1.5	12 hr	Aten
(17246) 2000 GL74	S/2004 (17246) 1	4.5 et 2 Km	2004 - Tamblyn et al (IAUC 8293)	230	?	Koronis ?
26308 1998 SM165	S/2001 (26308) 1	(# 1.9 mag)	2001 - Trujillo and Brown (IAUC 7807)	6000	?	SDO
(47171) 1999 TC36	S/ 2001 (1999 TC36) 1	(# 1.89 mag)	2001 - Trujillo and Brown (IAUC 7787)	8000	?	Plutino
(58534) 1997 CQ29	S/ 2001 (1997 CQ29) 1	(# 0.4 mag)	2001 - Noll et al. (IAUC 7824)	5200	?	Cubewano
(65803) 1996 GT	S/ 2003 (65803) 1	800 m et 150 m	2003 - Pravec et al. (IAUC 8244)	?	11.9 hr	Amor 2
(66063) 1998 RO1	S/ 2003 (66391) 1	ratio 0.4 minimum	2003 - Pravec et al. (MPML 24-Sep-03)		14.53 hr	Aten
(66391) 1999 KW4	S/ 2001 (1999 KW4) 1	1200 and 400 meters	2001 - Benner et al. (IAUC 7632)	?	17.45 hr	Aten
(66652) 1999 RZ253	S/ 2003 (1999 RZ253 ) 1		2003 - Noll et al. (IAUC 8143)	6300		Cubewano
(69230) Hermes	S/ 2003 (1937 UB) 1	both ~ 400 m	2003 - Margot et al. (IAUC 8227)	150 m	13.8 hr ?	Apollo 2
1990 OS	S/ 2003 (1990 OS) 1	300 m and 45 m	2003 - Ostro et al. (IAUC 8237)	> 600m	18 to 24 hr	Apollo 2
1998 ST27	S/ 2001 (1998 ST27) 1	min. ratio 1/3	2001 - Benner et al. (IAUC 7730)	4	~100 hr	Aten
1998 WW31	S/ 2000 (1998 WW31) 1	(# 0.4 mag)	2000 - Veillet (IAUC 7610)	1.2 arcsec	?	Cubewano
1999 DJ4	S/ 2004 (1999 DJ4) 1	420 et 200 m	2004 - Pravec et al (IAUC8316+8329)	> 700m	17.72 h	Apollo-2
2000 CF105	S/2002 (2000 CF105) 1	(# 0.87 mag)	2002 - Noll et al. (IAUC 7857)	<=23000	?	Cubewano
2000 CQ114	S/2004 (2000 CQ114) 1	( # ~ 0.5 mag )	2004 - Stephens et Noll (IAUC 8289)	5880 Km	?	Cubewano
2000 DP107	S/ 2000 (2000 DP107) 1	800 and 300 m (# 2.1 mag)	2000 - Margot and Nolan (IAUC 7496)	2.6 km	42.2 hr	Apollo 1
2000 UG11	S/ 2000 (2000 UG11) 1	230 and 100 meters	2001 - Nolan et al. (IAUC 7518)	?	18.4 hr	Apollo 2
2001 QC298	S/ 2002 (2002 QC298) 1	?	2002 - Noll and Stephens (IAUC 8034)	5000	?	Cubewano
2001 QT297	S/ 2001 (2001 QT297) 1	(# 0.55 mag)	2001 - Elliot et al. (IAUC 7733)	0.6 arcsec	?	Cubewano
2001 QW322	S/ 2001 (2001 QW322) 1	each 200 km (# 0.4 mag)	2001 - Kavelaars et al (IAUC 7749)	130000 km	4 years	Cubewano
2002 BM26	S/ 2002 (2002 BM26) 1	600 and 100 meters	2002 - Nolan et al. (IAUC 7824)	100 meters	< 72 hr	Amor 2
2002 KK8	S/2002 (2002 KK8) 1	500 and 100 meters	2002 - Nolan et al. (IAUC 7921)	?	?	Amor 2
2003 SS84	S/2003 (2003 SS84) 1	120 and 60 meters	2003 - Nolan et al. (IAUC 8220)	?	23.99 hr	Apollo 2
2003 UN284	S/2003 (2003 UN284) 1	(# 0.59 mag)	2003 - Millis and Clancy (IAUC 8251)	2.0 arcsec	?	Cubewano
2003 YT1	S/2004 (2003 YT1) 1	1000 et 180 mètres	2003 -Nolan et al (IAUC 8336)	?	30 h	Apollo-1
Other asteroids judged to be binary ( by radar, Hubble, occultations, lightcurves - NB: list not complete)
Asteroid	Orbital period in hr	Family	Discoverers of probable binary nature
7 Iris	?	Belt N°1	1995 - Mitchell et al.	Radar
12 Victoria	?	Belt N°1	1995 - Mitchell et al.	Radar
15 Eunomia	?	Belt N°1	1985 - Cellino et al.	Sep. 0.26 arcsec and # 1.0 mag
18 Melpomene	?	Belt N°1	Fernbank Observatory, USA	Satellite of 48 km at 750 km ?
39 Laetitia	?	Belt N°1	1985 - Cellino et al.	Sep. 0.13 arcsec and # 0.8 mag
43 Ariadne	?	Belt N°1	1985 - Cellino et al.	Sep. 0.10 arcsec and # 0.6 mag
44 Nysa	?	Belt N°1	1985 - Cellino et al.	Sep. 0.08 arcsec and # 1.4 mag
49 Pales	?	Belt N°1	Tedesco	Satellite of 50 km at 450 km ?
61 Danae	?	Belt N°1	1985 - Cellino et al.	Sep. 0.07 arcsec and # 1.5 mag
82 Alkmene	?	Belt N°1	1985 - Cellino et al.	Sep. 0.05 arcsec and # 1.1 mag
129 Antigone	?	Belt N°1	1977 - Scaltriti and Zapalla	Sep. 0.05 arcsec and # 1.7 mag
146 Lucina	?	Belt N°1	Arlot et al.	During occultation
164 Eva	?	Belt N°1	Schober et al.	During occultation
171 Ophelia	?	Belt N°1	Tedesco	Satellite of 30 km at 300 km ?
216 Kleopatra	?	Belt N°1	Cellino (1985) and Marchis(IAUC 7308)	Sep. 0.17 arcsec and # 0.2 mag
287 Nephthys	?	Belt N°1	Marchis et al ( via BDL )	Satellite at 111 km ?
361 Bononia	?	Hilda	Roger Venable ( 01/2002 )	During occultation
532 Herculina	?	Belt N°1	James McMahon	Satellite of 50 km at 1000 km ?
624 Hektor		Trojan-East	Cellino et al. (1985)	Sep. 0.08 arcsec and # 0.1 mag
772 Tanete	?	Belt N°1	IOTA  (MPML 24/04/04)	Satellite of 40km at 1200 km ? ( Occult.18-Apr-04 )
1089 Tama	0.6852	Belt N°1	Roy and Behrend (IAUC 8265)	Sép. 0"03 ( 20 km ) and # 0.5 mag ( ratio 0.7 )
1313 Berna	1.061	Belt N°1	Roy and Behrend (IAUC 8292)	Sép. 0"03 and # 0.7 mag
3671 Dionysus	27.72	Amor 3	Mottola and Hahn (IAUC 6680)
4492 Debussy	?	Belt N°1	Behrend et al (AUDE 21/03/04)	Eclipse of 0.5 mag
5407 1992 AX	(13.52)	Mars-crosser	Petr Pravec et al.
31345 1998 PG	(14.01)	Amor 2	Petr Pravec et al.
35107 1991 VH	32.69	Apollo 1	P. Pravec and G. Hahn
1994 AW1	22.40	Amor 1	Petr Pravec et al.
1996 FG3	16.14	Apollo 1	Petr Pravec et al.
1999 HF1	14.02	Aten	Petr Pravec (MPML 0-Mar-02)
2001 SL9	16.40	Apollo 1	Petr Pravec et al.
2003 QY90	?	SDO	J.L.Elliot et al. (IAUC 8235)	Sep. 0.34 arcsec / Pair unresolved
NB: 15 to 17% of NEAs larger than 200 m across might be binary asteroids.
Currently, binary asteroids appear to be less numerous amongst TNOs, and even less so in the Belt N°1 than amongst NEAs ( Harris - MPML 23-Nov-03)
Asteroids having companions would have different rotation periods according to orbital type ( Petr Pravec - MPML 20-Feb-03 ) :
- 4 to 6 hours for Main-belt objects with an average amplitude of 0.4 mag.
- 2 to 4 hours for Earth-crossers with a lower average amplitude of 0.1 mag.
Taxonomic distribution of asteroids
A little more than 2000 asteroids have had their taxonomic type determined, thanks to spectral analysis.
All of the various taxonomic types that exist have not yet been identified and their distribution as a function of their average distance from the Sun is still uncertain,
however two large groups dominate :
1) Asteroids of type S, covered with silicates, mainly in the inner part of the Belt N°1, and more than 30 km in diameter.
They represent around 20% of Main-belt objects.  Small objects of type S find their way in virtually any part of the Belt N°1.
2) Asteroids of type C, carbonaceous and very dark, numerous starting from the outer region of the Belt N°1, and representing 56% of the
Main-belt population.
- Various taxonomic types, combined in Group X, which comprises 24% of the population of the Belt N°1.
A new factor influencing the surface properties of asteroids has been recently introduced, namely the "space weathering process".
It is manifest as a phenomenon which alters asteroid surfaces through being subjected to aggressive ultraviolet solar radiation and
cosmic rays.
This process darkens asteroid surfaces, increasing the reddening of their spectra.
Recent "fragments" of S-type asteroids would in this way become Q-type asteroids having surfaces newly-exposed to solar radiation and space.
The albedo of NEAs of type S increase on average with decreasing diameter.
The spectral differences of NEAs should enable one to identify those that have resulted from recent ejection from the v6 and 3:1 resonances and which have
spent a very long time exposed to the Sun whilst transferring via the Mars-crossers to the region of the Earth's orbit.
There is a greater spectral diversity among the small asteroids than for the large asteroids, which by contrast seem to show sometimes different spectral types
to their surface.
Beyond 3.2 AU from the Sun, the vast majority of asteroids  have a very low albedo, but some notable exceptions do exist such as the albedos of
Pluto or of 2060 Chiron.
The Jupiter-Trojans and more distant asteroids are expected to be rich in water ice and volatile materials.
Their primordial constitution does not seem to have evolved much, except for their surface seeming to be made up of organic-complex solid material.
Jupiter-Trojans are characterised by surfaces having unremarkable reddish spectra with low albedos.
All Trojans of Jupiter are of spectral type D.
The spectra of Centaurs indicate the existence of various surface types characteristed by their very different spectral colours, from very red as with 5145 Pholus
to neutral as for 2060 Chiron which does not possess any dark irradiated coating.
Their spectral characteristics appear to approach those of the TNOs, indicating their probable origin in the Kuiper Belt.
Kuiper-belt objects should be composed of ices of H2O, CO, CO2 and of dust.
On going from the Centaur to the SKBO, there doesn't appear to be any marked change in the distribution of different spectral types as a function of distance from the
Sun, except for a reddening of surface colour.
Therefore, some TNO or Centaur objects show different colours which seem to arise from differently-combined actions altering the surface as well as
the action of impacts causing the appearance of sub-surface layers on TNOs.
Around 1/3 of the surface of 100-km TNOs would have been remodelled by impacts during the last 3.5 billion years.
The Plutinos would have been more affected by collisions, as there are very few of them with a bluish spectrum characteristic of the primordial TNO surface.
Current mineralogical types of asteroids and their albedo
Type	Albedo	Type of surface	Associated Meteorites
A	0.13 - 0.40	Rich in Olivine	Brachina
B	0.04 - 0.08		Carbonaceous Chondrites ?
C	0.03 - 0.07		Carbonaceous Chondrites (CM)
D	0.02 - 0.05		Kerogenes ?
E	0.25 - 0.60		Aubrites
F	0.03 - 0.06
G	0.05 - 0.09		Carbonaceous Chondrites ?
M	0.10 - 0.18		Enstatite Chondrites, Iron
P	0.02 - 0.06
Q	~ 0.20		Ordinary chondrites unaltered by space weathering
R	~ 0.40	Rich in Olivine
S	0.10 - 0.22		Iron-rich and ordinary Chondrites having suffered aging in space
T	0.04 - 0.11
V	~ 0.40	Rich in Pyroxene	Basaltic Achondrites ( HED )
A new 2002 classification of mineralogical types for asteroids
At the end of 2002, a new spectral classification was established following some intensive CCD work.  This is still in the process of analysis by the experts.
This classification arose from the SMASS II survey of Bus and Binzel indicating the existence, in the Belt N°1 of 3 large groups S, C and X, and some small
groups having very specific spectral signatures.
Group X is made up of sub-groups that cannot be classed in groups S and C, but spectrally is situated between S and C.
The subdivision of these groups depending on spectral particulars within the groups has given rise to a splitting into 26 different spectral
classes (or types) for the 1343 asteroids studied, with semi-major axes located from 2.10 to 3.78 AU :
Group S = Types A, K, L, Q, R, S, Sa, Sk, Sl, Sq and Sr
Group C = Types B, C, Cb, Cg, Cgh and Ch
Group X = Types X, Xc,Xe and Xk
Unusual Objects = Types D, Ld, O, T and V
Types Sa, Sk, Sl, Sq, Sr, Cb, Cg, Cgh, Ch, Xc, Xe and Xk have spectral types which are in part similar to other neighbours designated by lower-case suffixes.
They also correspond to an extent with the letters used previously, based on the older spectral analyses.
The previous asteroids of type E, M and P are reallocated in the different types within Group X .
The previous asteroids of type G and F are now assigned to the different types of Group C .
Other spectral classes will be added in the future to represent those very specific groups many of which will be further than the Belt N°1, such as
the class of very reddened asteroids ( e.g. 5145 Pholus )
Among the very specific types studied under SMASS II, there are :
- Asteroids of surface-type V, generally members of the Vesta dynamic family.  Some cases more distant than 4 Vesta are known : 956 Elisa,
the Floras 809 Lundia and 4278 Harvey, and 1459 Magnya situated in the outer region of the Belt N°1.
- Type O only has 4 members known : 3628 Boznemcova, 4341 Poseidon, 5341 Herakles and 1997 RT.
- the R spectral class also is represented by only 4 asteroids : 349 Dembowska, 1904 Massevitch, 2371 Dimitrov and 5111 Jacliff
- 1862 Apollo is the lead example of type Q comprising a dozen Earth-crossers. No minor planet from the Belt N°1 falls in this class.
- Objects of type K make up nearly one-half of the "Eos" dynamical family.
Mineralogical types for asteroids according to the new 2002 classification and their albedo
Type	Albedo	Type of surface	Associated Meteorites	Remarks
A	0.13 to 0.40	Rich in Olivine	Brachina	Belonging to fragmented objects ?
B	0.04 to 0.08		Carbonaceous Chondrites ?
C	0.03 to 0.09		Carbonaceous Chondrites (CM)	Notably the Themis and Hygiea families
D	0.02 to 0.05	cometary material ?		Jupiter-Trojans and beyond
K	~ 0.10 ?			especially the Eos family
O			Ordinary Chondrites L6 and LL6
Q	~ 0.20	Rich in Pyroxene	Ordinary Chondrites L4 and LL5	Currently only Earth-crossers
R	~ 0.40
S	0.10 to 0.22		Iron-rich and ordinary Chondrites	Floras and Eunomias notably
T	0.04 to 0.11
V	~ 0.40		Basaltic Achondrites ( HED )
Xe	0.25 to 0.60	presence of Troilite		Hungarias and inner edge of Belt N°1
X ( ex-M )	0.10 to 0.18		Enstatite Chondrites, Iron, Nickel	cores of fragmented asteroids ?
NB: The links between the taxonomic and mineralogical types are not yet perfectly established so that one (current) spectral class perhaps may not be representative of
a specific mineralogy.
Small asteroids and recently-created Earth-crossers can have more varied mineralogical types being less altered (over time) than the larger asteroids, which, themselves,
can represent varied mineralogies, considering the more significant surface types ( e.g. 64 Angelina and 434 Hungaria ).
Asteroids already visited by probes from Earth
Asteroid	Encounter Date	Probe
951 Gaspra	29-Oct-1991	Galileo	Flypast at 1600 km
243 Ida	28-Aug-1993	Galileo	Flypast at 2400 km, and discovery of Dactyl
253 Mathilde	27-Jun-1997	NEAR	Flypast at  1212 km
9969 Braille	29-Jul-1999	Deep Space 1	Flypast at about 26 km, 'blind'
433 Eros	23-Dec-1998	NEAR	Flypast at 3830 km
2685 Masursky	23 janvier 2000	Cassini	Flypast at 1.6 million km
433 Eros	Arrival 14-Feb-2000	NEAR-Shoemaker	12-Feb-2001 : Landing of the probe on Eros
5535 Annefrank	02-Nov-2002	Stardust	Flypast at  3300 km
Future explorations of asteroids by terrestrial space probes
Asteroids	Mission leaves	Probes	Flypast date	H	Zone	Remarks
25143 Itokawa	May 2003	Muses-C  ( ISAS - Japan )	Summer 2005 : 4.5 months + samples	19.2	Apollo 1	(ex -1998 SF36)
21 Lutetia	March 2004	Rosetta ( ESA )	10 July 2010	7.35	Main Belt	type Xk (ex-M)
2867 Steins	MArch 2004	Rosetta ( ESA )	05 September 2008	13.19	Main Belt	type S (IAUC 8315)
Pluto-Charon	January 2006	New Horizons ( NASA )	2015 : duration 6 months	- 1.6	Plutinos
TNO	January 2006	New Horizons ( NASA )	not yet chosen	?	?
1 Ceres	May 2006	Dawn ( NASA )	Arrival in 2014	3.34	Belt N°1	C
4 Vesta	May 2006	Dawn ( NASA )	Arrival in 2010 - 1 year in orbit	3.20	Belt N°1	V
Main-belt Asteroids	May 2006	Dawn ( NASA )	not yet chosen	?	Belt N°1
Near-Earth asteroids which can be most easily visited by space probes
Between now and 2013, 27 NEAs approaching very close to the Earth could be easily visited, of which 5 have very low launch costs, plus two others of great interest :
Asteroid	Family	Flypast date possible	Specifics
1996 FG3	APOLLO 1		H = 18.2 - Probable binary asteroid, of type C
1996 XB27	AMOR 1	2004 or 2005	H = 22.0 - 200 meters across
25143 Itokawa	APOLLO 1		H = 19.2 - 690x300 meters in size = Target for MUSES-C
1998 KY26	APOLLO 1	2011 or 2013	H = 25.5 - 30 meters across
			Rotation period : 11 min / Carbonaceous Chondritic surface
1999 AO10	ATEN	January 2006 or April 2007	The most accessible
2000 EA14	APOLLO 1		H = 20.9 - 320 meters diameter
2001 CQ36	ATEN		H = 22.6 - 150 meters across
The most successful numbered Asteroid Discoverers as of 20-May-2004
From 1801 up to 1891, all minor planet discoveries were visual discoveries !
The greatest visual Discoverer was the Austrian professional astronomer, Johann Palisa, with 122 discoveries, some of which were of magnitude 15, at a
time when star atlases were virtually non-existent.
From 1891, starting with the discovery of 323 Brucia, up until the 1990s, the period of photographic discovery replaced visual discovery.
The German professional astronomers, Max Wolf and Karl Reinmuth were the first great photographic discoverers, with respectively 228
and 395 asteroids, when discovery follow-up was still not very easy.
Later, C. J. van Houten, I. van Houten-Groeneveld and Tom Gehrels became great photographic discoverers with to this day 3232
discoveries made as part of the "Palomar-Leiden Survey" of 1960 ( Objects PLS ) and of the three "Palomar Trojan Surveys" ( Objects T-1, T-2, T-3 ).
Working during both the photographic and CCD periods, Eric Elst has to date been the greatest individual discoverer of Asteroids, with 2979
discoveries and 69 co-discoveries.
The current period of CCD cameras and the introduction of powerful automated telescopes has permitted a virtual explosion in the number of discoveries :
3524 objets for NEAT, 4169 for Spacewatch, 4238 for LONEOS and 40515 for LINEAR on May 20,2004 !!
Amateurs equipped with CCDs have not been idle despite their more modest means.
The most prolific are the Japanese T.Kobayashi with 2117 discoveries until 1991, the Croatian Korado Korlevic with 881 asteroids + 99 co-discoveries
and the two Japanese duos K. Endate - K. Watanabe ( 691 discoveries ) and Ueda - Kaneda ( 559 discoveries ) .
The 12 greatest discoverers and their total discoveries as of 06-May-04 are ( Source MPC ) :
LINEAR	40515		Automated Observatory		USA
LONEOS	4238		Observatoire automatisé		USA
Spacewatch	4169		Observatoire automatisé		USA
NEAT	3524		Observatoire automatisé		USA
Van Houten and Gehrels	3232		Professional Observatory		Holland - USA
Elst	2979	+ 69 co-découvertes	Professional Observatory		Belgium
NEAT	2117	+ 2 co-découvertes	Automated Observatory		USA
Kobayashi	1511		Amateur		Japan
CSS	1143	+ 287 co-découvertes	Professional Observatory		USA
Bus	881	+ 99 co-découvertes	Professional Observatory		USA
Korlevic	691		Amateur		Croatia
UESAC	881		Professional Observatory		Sweden
Ueda and Kaneda	691		Amateurs		Japan
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Michel-Alain Combes	"La menace du ciel" ( http://astrosurf.com/macombes )					-
Apostolos Christou	The nearest of Near Earth Asteroids ( http://star.arm.ac.uk/~aac/astrodyn.html )					-
C.L. Dandy et al.	Optical colors of 56 near-Earth objects: trends with size and orbit					<GF:qo>
John Davies et al.	The lightcurve and colors of Unusual Minor Planet 1998 WU24 - Icarus 150, 69-77 (2001)					<GF:mp>
M. Delbo et al	Keck observations of near-Earth asteroids in the thermal infrared - Icarus 166 (2003) 116-130					<GF:qu>
C. De Berg / J. Romon	Les objets de Kuiper - L'Astronomie Vol.115, January/February 2001 pages 78-89					-
Dell'Oro et al.	The role of Families in Determining Collision Probability in the Asteroid Belt N°1 - Icarus 153, 52-60 (2001)					<GF:mb>
A. Doressoundiram et al.	Multicolor Photometry of Trans-Neptunian Objects - Icarus 154, 277-286 (2001)					<GF:pd>
Daniel D. Durda et al.	A new Observational Search for Vulcanoids in SOHO/LASCO Coronograph images - Icarus 148, 312-315 (2000)					<GF:mi>
Eric Elst	On the discovery of faint Trojans ( http://www.astro.hr/mace2002/abstracts/abstracts.html )					-
Gérard Faure	Private Databases and statistical works On Asteroids					-
Marcos Florczak et al.	A Visible Spectroscopic Survey of the Flora Clan - Icarus 133, 233-246 (1998)					<GF:qm>
Marcos Florczak et al.	Discovering New V-Type Asteroids in the vicinity of 4 Vesta - Icarus 159, 178-182 (2002)					<GF:oc>
Cr. and Cl Froeschle	Les astéroides - La Recherche N°183 - December 1986					<GF:PU>
Gabryszewski/Wlodarczyk	The resonant dynamical evolution of small body orbits among giant planets					<GF:qa>
	Astronomy and Astrophysics 405, 1145-1151 (2003)
Alessandro Giuntini	Twice than expected ( Tumbling stone - Issue 13 - http://spacegAUrd.ias.rm.cnr.it/tumblingstone/issues/ )					-
J.C.Gradie et al.	Families - Asteroids ( Gehrels -1979 )					<GF:FM>
Bill Gray	Asteroid Families: definitions (http://www.projectpluto.com/mp_group.htm)					<GF:lb>
Bernard Guillaud-Saumur	Orbital elements of comets ( http://www.astrobgs.dyndns.org/astro/cmt2004/comet.txt)					-
Alan W. Harris	Asteroid Lightcurve Catalog ( http://cfa-www.harvard.edu/iau/lists/LightcurveDat.html )					-
W.K. Hartmann	Current, Unusual Asteroids Models ( Table I ) - Asteroids (Gehrels - 1979)					<GF:JX>
IAA - Russie	"Ephemerides of Minor Planets" from 1985 to 2003					-
IAUC	International Astronomical Union Circulars: http://cfa-www.harvard.edu/iau/cbat.html					-
A.M.	A "negative Gravity" Asteroid ( News Notes) - Sky and Telescope, February 2002, page 24					<GF:me>
B.Gladman et al.	Evidence for an Extended Scattered Disk - Icarus 157, 269-279 (2002)					<GF:ng>
Alan W. Harris	"On the Slow Rotation of Asteroids" - Icarus 156, 184-190 (2002)					<GF:nw>
P.M.Janiczek et al.	Resonances and Encounters in the Inner Solar System - The Astronomical Journal Vol.17, N° 9 (November 1972)					<GF:GC>
R.Jedicke / T.Metcalfe	The Orbital and Absolute Magnitude Distributions of Belt N°1 Asteroids - Icarus 131, 245-260 (1998)					<GF:kl>
R.Jedicke et al.	Observational Selection Effects in Asteroid Surveys and Estimates of Asteroid Population Sizes - ( Asteroids III )					<GF:web>
David Jewitt	The Kuiper Belt  ( http://www.ifa.hawai.edu/~jewitt/kb.html )					-
M.Kelley / M.Gaffey	"9 Metis and 113 Amalthea: A Genetic Asteroid Pair" - Icarus 144, 27-38 (2000)					<GF:lr>
Z. Knezevic / A. Milani	Proper elements catalogs and asteroid families - Astronomy and Astrophysics 403, 1165-1173 (2003)					<GF:ql>
Y.Kozai	Dynamics of families - Asteroids ( Gehrels -1979 )					<GF:FM>
A. Kryszczynska et al.	Puzzling rotation of asteroid 288 Glauke - Astronomy and Astrophysics 404, 729-733 (2003)					<GF:pz>
H.Levison / A.Morbidelli	Forming the Kuiper Belt by the Outerward Transport of Objects During Neptune's Migration - Nature November 27,2003					-
F. Marzari et al.	Collisional Evolution of Asteroid Families - Icarus 113,168-187					<GF:ke>
F. Marzari et al.	Origin, Aging, and Death of Asteroid Families - Icarus 142, 63-77					<GF:lp>
Gianluca Masi	Searching for inner-Earth Objects: a possible ground-based approach - Icarus 163, 389-397 (2003)					<GF:qp>
Jean Meeus	An Asteroid's Remarkable orbit - Sky and Telescope, December 1997					<GF:ig>
W.Ip / R.Mehra	Resonances and librations of some Apollo and Amor asteroids with the Earth - The Astron. J., Vol 78, N° 1 (Feb-1973)					<GF:GB>
P.Michel / P.Tanga et al.	Formation of Asteroid Families by Catastrophic Disruption: Simulations with Fragmentation and Gravitational					<GF:od>
	Reaccumulation - Icarus 160, 10-23 (2002)
T.A. Michtchenko et al.	Origin of the Basaltic Asteroid 1459 Magnya: A Dynamical and Mineralogical Study of the Outer Belt N°1					<GF:oi>
	Icarus 158, 343-359 (2002)
A.Milani / P.Farinella	An asteroid on the brink - Icarus 115, 209-212 (1995)					<GF:kf>
Minor Planet Center	Various data on asteroids ( http://cfa-www.harvard.edu/iau/lists/MPLists.html )					-
	Files of asteroid orbital elements ( http://cfa-www.harvard.edu/pub/MPCORB/ )					-
Minor Planet Mailing List	"mpml@yahoogroups.com"   and   MPML Home page: "http://www.bitnik.com/mp"					-
M.Morais / A.Morbidelli	The Population of Near-Earth Asteroids in coorbital Motion with the Earth - Icarus 160, 1-9 ( 2002 )					<GF:oq>
A. Morbidelli et al.	From Magnitudes to Diameters: The Albedo Distribution of Near Earth Objects and the Earth Collision Hazard					<GF:oh>
	Icarus 158, 329-342 (2002)
A. Morbidelli et al.	The shallow magnitude distribution of asteroid families - Icarus 162, 328-336 (2003)					<GF:pw>
A. Morbidelli / H. Levison	Scenarios for the Origin of the Orbits of the Trans-Neptunian Objects 2000 CR105 and 2003 VB12					<GF:qw>
	Astrophysics, abstract astro-ph/0403358
Morbidelli/Vokrouhlicky	The Yarkovsky-driven origin of near-Earth asteroids - Icarus 163, 120-134 (2003)					<GF:qk>
T. Mothé-Diniz et al.	Distribution of taxonomic classes in the Belt N°1 of asteroids - Icarus 162, 10-21 (2003)					<GF:px>
NASA	Asteroid and Comet Impact Hazards (http://impact.arc.nasa.gov/reports/spaceguard/sg_5.html)					<GF:jj>
D.Nesvorny et al.	The Recent Breakup of an Asteroid in the Main-Belt Region ( http://www.swri.org/9what/releases/15asteroid.htm )					MPML 13-Jun-02
D.Nesvorny et al.	The Flora Family : A Case of the Dynamically Dispersed Collisional Swarm ? - Icarus 157, 155-172 (2002)					<GF:nf>
D.Nesvorny / L.Dones	How long-Lived Are the Hypothetical Trojan Populations of Saturn, Uranus and Neptune ? - Icarus 160, 271-288 ( 2002 )					<GF:ol>
Joel Parker	The Kuiper Belt Electronic Newsletter - http://www.boulder.swri.edu/ekonews/					-
Jason Perry	http://members.fortunecity.com/volcanopele/Moon_list.htm  (Jason Perry - MPML 01-Apr-01) .					-
J-M.Petit / A.Morbidelli	The primordial excitation and clearing of the Asteroid Belt- Icarus 153, 338-347 (2001)					<GF:ma>
Petr Pravec et al.	Fast Rotating Asteroids: 1999 TY2, 1999 SF10 and 1998 WB2 - Icarus 147, 477-486 (2000)					<GF:mo>
P.Pravec / A.W.Harris	Fast and Slow Rotation of Asteroids - Icarus 148, 12-20 (2000)					<GF:mk>
Petr Pravec	Binary Near-Earth Asteroids ( http://www.asu.cas.cz/~asteroid/binneas.htm )					-
A.S. Rivkin et al	Spectroscopy and photometry of Mars Trojans - Icarus 165 ( 2003) 349-354					<GF:ra>
Sylvain Rondi et al.	Les troyens du système solaire ( http://dess-s2.obspm.fr/~rondi/3c/menu.htm )					-
Petr Scheirich	Asteroid Groups  ( http://sajri.astronomy.cz/asteroidgroups/groups.htm )					-
Brian Skiff	List of Damocloids ( ftp://ftp.lowell.edu/pub/bas/damocloid )					-
S.M.Slivan et al.	Spin vectors in the Koronis family: comprehensive results from two independent analyses of 213 lightcurves					<GF:pm>
	Icarus 162, 285-307 (2003)
David Tholen	Personal communication ( E-message of 15-Apr-2002 )					-
J. Toth / L. Kornos	Close approaches of Very Small Near Earth Objects and their possible detection in the Earth-Moon vicinity					<GF:pb>
	( Acta Astron. et Geophys. Univ. Comenianae XXIV, 61-70 (2002) )
K.Tsiganis et al	Short-lived asteroids in the 7/3 Kirkwood gap and their relationship to the Koronis and Eos families					<GF:rd>
J. Virtanen et al.	Orbit computation for transneptunian objects - Icarus 161, 419-430 (2003)					<GF:pz>
D.Vokrouklicky et al.	The Depletion of the Putative Vulcanoid Population via the Yarkovsky Effect - Icarus 148, 147-150 (2000)					<GF:mj>
Brian Warner	CALL homepage ( http://www.MinorPlanetObserver.com/astlc/default.htm )					-
	Five brightest Apparitions of numbered Asteroids ( http://www.MinorPlanetObserver.com/htms/FiveBrightest.html )					-
Richard M. Williamson	Observation of a secondary extinction during the occultation of SAO 114159 by (18) Melpomene - Astron.J., Vol.85, N°2 (Feb.1980) <GF:IK>
V.Zappala et al.	Asteroid families. I. Identification by hierarchical clustering - Astron. J. 100, 6th  December 1990					<GF:ao>
V.Zappala et al.	Asteroid families: Search of a 12487 Asteroid Sample Using two Different Clustering techniques					<GF:kd>
	Icarus 116, 291-314 (1995)
B.Zellner et al.	The Large-scale Structure of the Asteroid Belt - Icarus 62, 505-511 (1985)					<GF:LQ>
?	The real Asteroid Belts ( News Notes) - Sky and Telescope, March 1986					<GF:NO>