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.