Astrometry is that part of Astronomy that takes care of meausuring the position of all celestial bodies in the sky. Applied to the comets and asteroids becames Solar system Minor bodies Astrometry.
Why to follow with difficulty these small object that seem so meaningless ?
Asteroids, or minor planets, are irregular shape celestial bodies with dimensions that only for the few geatests of them can reach hundred of miles. The majority is turning aroun the Sun in a belt between the orbits of Mars and Jupiter, distant more than one hundred million of miles from Earth.
Physicist estimate that this belt contains some hundred of thousand asteroids, but we know with precision the orbit of only twenty thousend of them. Minor planets are studied to know their number, their physical properties, their spatial distribution, to understand how ana when they are born (first stages of the evolution of our Solar system), to evaluete the probabilities and possibilities of collision with our Earth. Nowaday almost two thousand asteroids are found "able" to cross terrestrial orbit and thus potentially dangerous for us. The discovery and control of this kind of objects, for scientists NEOs (Near Earth Objects), is very important due to the catastrophic chain of events in the terrestrial byosphere inducted by the impact with Earth of a body of only less than a mile in diameter.
To discover and monitor continuously all asteroids non-professional astronomers all around the world are necessary.
CCAF, involved in this field from more than 10 years, contributed with the identification (discovery) of more than 140 new asteroids. Among these, 1997 AQ18 is the first and only NEO discovered in Italy in the Apollo class, objects considered very dangerous for the Earth. Another unusual astreoid is 1996 AX1, with a particular eccentric orbit, while (9431) e (13387) are two Trojans, minor planets that move synchronous before or after Jupiter in particular stable balance points (Lagrangian).
As often happens in many scientific field asteoird discoverers are allowed to give a nomination to the object discovered. In this case all takes place after years from first observation when the new orbit becames paricularly stable (well determined). Among those discovered at Farra Observatory the first numbered, (6501), has become "Isonzo" to represent all those contribute made possible the birth and the growth of CCAF. After Isonzo many others were added.
In the last years the search for new objects has become harder due to many more professional observatories boprn to systematically find all NEOs crossing our skies (LINEAR, LONEOS, NEAT, Catalina Sky Survey, ODAS, Spacewatch): these automatic stations are able to "rake up" all in the sly, comets included. Non-professional activity is shifting slowly to their "follow-up", to have a sufficient number of observations to determine a more precise orbit and to know with less uncertainties the chances that an object hits the Earth in a near future.
CCAF partecipates at this "hunt" from a couple of years in the NEO Coordination Page, a worlwide connection of many observatories to pursue the objects listed in the NEO Confirmation Page.
In 1999 have been issued 71 circulars MPEC with 323 meausures of 64 NEOs obtained from CCAF.
In Italy works the Italian Astrometrists Group, formed by many observatories along the whole peninsula that are constantly in touch to exchange impressions, experiences, help requests and self-made software. At GIA site is available the Guida per l'Astronomo dilettante (Amateur Astronomer Guide in italian) that helps who likes to start this activity.
A must ti read is also the Minor Bodies Astrometry Guide, updated by Minor Planet Center.
Very useful is also the American minor planets mailing-list.
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